Everyday meaning flows like resin in the cold. Explanation of proverbs from the point of view of physics. Physics and folk signs about the weather

25.01.2010, 19:32

There are leaks in the pipe, help me figure it out.
In my dacha on the second floor there are leaks in a pipe. I can’t understand why, help me figure it out. Leakage occurs only when the fireplace is lit.
The streaks appeared at the beginning of severe frosts when the temperature dropped below -10 degrees.
The fireplace-stove has been in operation since February 2009, then there were also frosts, but not so long and severe. There were no drips. There was no spring or autumn.
The stove maker who installed the “shield” says that he doesn’t know what’s wrong, like it’s most likely condensation that forms between the ceiling of the 2nd floor and the roof.
But there are doubts, since 1) The leaks are continuous. 2) The water is yellow and smelly - it smells strongly of smoked meat. In short, “sos”!! On the second floor there is such a stench that it is no longer possible to sleep.

Anatoly A

25.01.2010, 19:46

Andrey, we need to insulate the pipe between the roof and the ceiling, it’s cold there, and there’s also a draft, and all the problems will be eliminated.

25.01.2010, 23:55

thanks in advance to the experts

26.01.2010, 00:48

Andrey, I have the same situation. On the 2nd floor the chimney is wet. I come to the conclusion that it is condensation. It forms at a height of 4-5 m from the boiler and protrudes if there is no metal in the pipe. case. I have an asbestos-cement pipe inside - I was greedy for stainless steel, now I’m racking my brains.

Zhirnov Vladimir

26.01.2010, 01:58

Anatoly, thanks for the advice. The stove maker also talked about this. But I have this question in doubt! If this is condensation, then why is it brown and smoked?? Did it form from inside the stove? It should be as clean as a tear!! And why are the seams between the bricks wet and seem to be leaking? Or maybe condensation is passing through the cement from the inside? could this be? And another question - how to properly insulate a brick pipe in the attic space, so to speak, technology....
thanks in advance to the experts
Moisture comes out from inside.

There is a diagram.

26.01.2010, 02:48

Moisture comes out from inside.
It is useless to insulate the pipe itself, the brick is still cold.
Perhaps a sandwich insert will help. The reason is the design of the furnace.
There is a diagram.
Good day! Dear stove makers, what can you say about this material “Furanflex”, and the technology too? I read it on the Internet and I’m wondering if it will help get rid of condensation and damp plaster on the chimney? Thanks in advance.

Anatoly A

26.01.2010, 09:54

Ana]Andrey the pipe is placed up to the roof using clay mortar, and higher up using cement mortar. Your pipe is made of a high grade of brick M250, and maybe higher. While it’s winter, you need to wrap it with any non-flammable material, i.e. wrap it with insulation, in the summer you need to cover it with 7 cm of foamed gas silicate, not shoving any pieces of iron or anything into the pipe will help, extra costs.

Kataev Oleg

26.01.2010, 10:15

It won’t help to push any pieces of iron or anything into the pipe, extra costs.
That's right, after the piece of iron (it will flow down) - you'll have to install a condensate collector, but it will stink on the 1st floor too.

The reasons may be: violations of GOSTs - an umbrella (which should not exist at all), condensation from the smoke flows onto the pipe very low, it is cold (and along the outer surface of the pipe, if there are cracks, it drips inside), or the pipe is already soaked through with condensate with increased heating of the stove and fireplace with strong dilution with air and a decrease in smoke temperature.
Kataev Oleg
In the attic, condensation from the air can mix with pipe condensation; insulating the pipe there will not hurt.
I looked at the picture - condensation can (should) form in the attic insulation layer. Are there any drips above?

Zhirnov Vladimir

26.01.2010, 15:56

Anatoly A

26.01.2010, 16:33

Oleg, the inner contour of the sandwich will warm up faster than a brick.
It is useless to insulate bricks in the attic. Vladimir, answer why in the old days walls were made meter long, but now 2 bricks are enough.

Zhirnov Vladimir

26.01.2010, 16:59

Anatoly, insulate the pipe. Don’t forget to climb onto the roof and place a view on the pipe.

26.01.2010, 17:06

The stove maker who installed the “shield” says that he doesn’t know what’s wrong, like it’s most likely condensation that forms between the ceiling of the 2nd floor and the roof.
Anrey, increase the temperature of the exhaust gases. It can be increased if: 1) keep the forward stroke valve slightly open 2) increase the area of the grate 3) remove one channel in the panel. It could also be due to damp wood.

26.01.2010, 17:06

Thanks everyone for your comments. But I still didn’t understand what to do. There are many opinions. It’s 100% impossible to install anything inside the pipe, it’s not serious. Drip from the outside - from the umbrella, flow down the outside - there are a few drips from the umbrella, but they do not get inside, there are also traces of drips on the outside of the pipe on the street, but they were there when 40 cm of snow fell. We cleaned off all the snow around the pipe. For the second weekend I’ve been monitoring the pipe on the roof to make sure no drips or drops get inside under the roof. The photo shows that everything is dry, there are no marks. This can be done to insulate the attic. The main thing is that it helps. Maybe there are other opinions???

26.01.2010, 17:13

26.01.2010, 17:23

Yes, one more thing - the firewood is really not very dry, I’ll try to pull out the valve, although this will reduce the heating of the shield, but oh well. increase the area of the grate?? It seems I don’t have it... removing one channel in the shield is just destroying the shield, it won’t work. All this is good, but the main question remains, why is condensation smelly? Why! where does it come from!! How do the channels run in your shield? if it’s vertical, then there’s nothing complicated - you break through the wall of the last channel at the bottom. No gatekeeper: o, what kind of fireplace do you have? - open? The condensation stinks, but because it is mixed with soot!

Anatoly A

26.01.2010, 17:31

You didn't answer what kind of brick it is.

26.01.2010, 17:52

Anatoly A - Baltic brick, I forgot the name.
sasha - cast iron fireplace Swedish Jotul "3", I'll attach a photo in a minute. Well, we had a little fun (no offense). How can leakage be mixed with soot?? This is leaking soot inside; by the way, it also flows through the cleaning doors like from a faucet for the first 5-10 hours of heating. Well, this is fixable and understandable. But the smoked ones are leaking on the outside - this is an incomprehensible problem. Looking forward to your comments, thanks in advance

26.01.2010, 17:57

Yes, and breaking the channel in the shield is not serious, it’s easier to open the forward damper only then, in severe frosts, until the brick really warms up

Anatoly A

26.01.2010, 18:00

Andrey was amused, the Baltic states are big.

26.01.2010, 18:04

I have no memory at all, I’ll write down the name in a minute.

26.01.2010, 18:14

Alexander Batsulin

26.01.2010, 18:25

I think you have a long-burning stove (How long does a stack of wood burn?)
If this is the case, then you cannot attach a shield to it. And the tube needs to be made into an insulated sandwich. This can be corrected by changing the combustion mode to intense in the potbelly stove.

26.01.2010, 18:31

How can leakage be mixed with soot?? It’s leaking soot inside; by the way, it’s also leaking through the cleaning doors
When the brick is completely saturated with “tar”, even on the first floor, then you will understand that the condensation comes with soot, although now it is still filtered by the brick: d. The temperature of the exhaust gases can be increased if you put a stainless steel screen on the glass of the combustion door, and always heat in cold weather with a completely open ashpit - it also increases the T, you can also insulate the “Yutul” itself :(

26.01.2010, 18:31

Exactly. Before doing all this, I consulted with three stove makers and 2 companies on the topic that I needed. Everyone approved and recommended just such an option so that the brick would not crack, etc. A fireplace or just a potbelly stove, a small shield, a brick chimney. Those. The reason is that we heat only on weekends. The stove has been in the cold for 5 days. In my old house there is only brick, and the firebox too. In 2 seasons, the whole stove was cracked. The stove makers came and looked and they said you can’t heat bricks quickly and intensely in cold weather. And so it happened. That’s why we did it with a fireplace - all the power of the fire is there - the brick is not exposed to strong heat - it gradually warms up. The idea was this. How can we spoil the brick? Unclear...

26.01.2010, 18:35

26.01.2010, 18:36

How can we spoil the brick? It’s not clear... Condensation will spoil it, and then it will stink even in the summer.

26.01.2010, 18:47

Well, of course, I’m not a stove builder, so I consulted before construction. Nobody said a word about condensation. Now there is a problem and somehow it needs to be solved. The fool should have worked for a stove maker as an assistant for a year :)

Anatoly A

26.01.2010, 18:51

Andrey, everything is clear for such a potbelly stove, the pipe 380x520 is a lot, you need 380x380, that is, close half of the outlet hole on top of the pipe.

Zhirnov Vladimir

26.01.2010, 18:56

The potbelly stove must be heated intensively, plus heat loss from it.
You need a brick firebox instead of a potbelly stove, or an insert into a sandwich pipe.
To do this, the pipe must be repositioned.

Anatoly A

26.01.2010, 19:11

Yes, it’s interesting how a company could recommend a shield for such a potbelly stove, it’s not known what channels, a five-piece pipe, it’s impressive.

26.01.2010, 19:25

pipe five, impressive. The only way out is to disassemble the five-piece pipe to the ceiling of the second floor, insert a valve and exit above the valve with a 4-piece pipe.

Alexander Batsulin

26.01.2010, 19:30

wood burns with an open ashpit - 30-45 minutes
in almost smoldering mode - 3-4 hours

I would suggest just not using the smoldering mode.

And how much wood burns in 30-45 minutes?

Zhirnov Vladimir

26.01.2010, 19:39

There is a diagram of the shield. At least he's warming up.
All advice will be like a poultice for the dead.

26.01.2010, 19:49

I would suggest just not using the smoldering mode.
I think if you heat intensively, there will be no condensation. You can use a thermocouple in the valve slot to check the temperature before redoing the pipe.

And how much wood burns in 30-45 minutes? Alexander, of course you need to heat it intensively, but for such a stove the diameter of the pipe at the firebox nozzle is like 13 cm, which means the output should be about the same, and not 2 times larger.

Kataev Oleg

26.01.2010, 20:01

Oleg, the inner contour of the sandwich will warm up faster than a brick.
It is useless to insulate brick in the attic.
I did not propose to insulate the pipe, I am generally against any insulation in the house, I suggested insulating the pipe from condensation - according to the description, this is condensation from the attic air mixed with smoke or condensate from it.
Kataev Oleg
Let me return to the assumption - condensation forms in the insulation layer on top from warm air from the attic, which flows down the pipe, and the pipe is apparently already soaked through with condensate from the smoke. Everyone has already given advice - to warm up the pipe with intense combustion.
Kataev Oleg
Check the integrity of the attic insulation vapor barrier, if any.

Alexander Batsulin

26.01.2010, 20:18

Alexander, of course you need to heat it intensively, but for such a stove the diameter of the pipe at the firebox nozzle is like 13 cm, which means the output should be about the same, and not 2 times larger.

I still don’t understand how the comrade drowns?

26.01.2010, 20:28

I still don’t understand how the comrade drowns? With a shield, in order to warm it up, the stove needs to be heated intensively; it cannot be heated by slow burning.

Alexander Batsulin

26.01.2010, 21:27

So how does HE drown? ------Andrey?

Blagov Alex

26.01.2010, 22:25

Good health to everyone! Listen to Zhirnov, he says, remake the firebox. Condensate is released during the firebox in every firebox and in order to evaporate it you need a temperature and draft. But I understand that you don’t have it. Especially from pine firewood. And pine also releases resin, which at low temperatures is deposited on walls. In short: the valve is fully open, the blower is at max. birch and aspen firewood!

26.01.2010, 23:22

I understand the corrective measures. 1) Insulate the chedda part 2) heat at full power 3) if possible, do not push the valve to full 3) Switch to birch, aspen. (I took 50/50 coniferous firewood/aspen birch, so I saved a little. And there won’t be clean birch until the summer. I’ll have to add more heat.) I leave reworking the pipe as an emergency option, if it doesn’t help at all. I really wouldn’t want the resin waste to pass through the brick onto the outer surface. This is some kind of fantasy

Alexander Batsulin

26.01.2010, 23:55

And these three to five hours - normal combustion or smoldering?

In your case, cancel smoldering altogether. Smoldering was invented for non-heat-intensive potbelly stoves in order to extend the heat transfer over time. When smoldering, the combustion is prolonged; the power released in the firebox is insufficient to maintain the required temperature in the cold (attic) brick pipe. Hence the condensation. You have a heat-intensive stove with a shield - there is no need for smoldering mode.

Anatoly A

27.01.2010, 10:27

Thanks everyone for your help. I'll tell you a little. I heat it like this - straight to full for 1 hour, then I close the damper. It is already walking along the shield until the house heats up and I make it smaller. This is about another 3-5 hours. Then at night there is more firewood and the economy mode is almost smoldering. In the morning, again, it was completely burning for 1-2 hours, then again almost smoldering. But this is when the frost is -10 -30 degrees.
Why is the chimney one and a half bricks? The stove maker made the calculation based on the size of the fireplace door so that it wouldn’t smoke. By the way, everything is okay in this regard.
I understand the corrective measures. 1) Insulate the chedda part 2) heat at full power 3) if possible, do not push the valve to full 3) Switch to birch, aspen. (I took 50/50 coniferous firewood/aspen birch, so I saved a little. And there won’t be clean birch until the summer. I’ll have to add more heat.) I leave reworking the pipe as an emergency option, if it doesn’t help at all. I really wouldn’t want the resin waste to pass through the brick onto the outer surface. This is some kind of fantasy Andrey, the entire stove needs to be completely redone, all measures are useless, extra money and nerves.

27.01.2010, 15:57

Burning goes on full for 3-5 hours. Remodeling the stove will be oh so difficult. Well, anyway, only in the summer. I’ll try until summer, maybe insulating the pipes in the attic space will help, and they also advised me to insulate the part of the pipe that is outside - make a box with insulation, who knows, what if it helps??

Alexander Batsulin

27.01.2010, 17:37

For starters, just try not to use the smoldering mode. For fun, insert a thermocouple (500 rubles) into the slot of the valve.

02.02.2010, 16:35

Ivan Belarus

02.02.2010, 21:25

here - this weekend the combustion is only at full mode, the damper is open directly. There were some drips, but much less and only on the first day of heating. I hope that insulating the attic pipes will solve the problem. I’m waiting for zero temperatures to disassemble the ceiling of the 2nd floor. What kind of stove is there that you have to burn for 1 hour without heating and then another “3-5” hours to warm up. Well, gluttonous! In short, wait until the summer and redo it, because this one ---( I don’t know how to make it softer:)) bad.

Blagov Alex

03.02.2010, 00:24

Insulation will not help! The pipe will freeze within a week anyway.

10.02.2010, 23:49

What kind of stove is that that needs to be heated for 1 hour and then another “3-5” hours to warm up? Well, gluttonous! In short, wait until summer and redo it, because this one (I don’t know how to make it softer :)) is bad.
we are talking about warming up a house on 2 floors - from -15 to +20

Ivan Belarus

11.02.2010, 08:50

We are talking about warming up a house on 2 floors - from -15 to +20, anyway, heating directly for an hour is nonsense (buzz word :)), that’s a lot of firewood almost wasted! The potbelly stove is designed for a smaller shield, but you have what is in the photo and something else that is not visible. The shield is L-shaped. And they never mentioned how it was made inside - channels or caps. But everything affects traction. By the way, the stove maker (Misha) warned you about the size and condensation.

15.01.2011, 22:52

Dear forum members, Happy New Year! I have to raise this topic again. This summer I rebuilt the oven, there was a Swede with three horizontal passages, from the line of the stove above it was laid out on edge. I added another passage and extended it due to the drying compartment. For more heat capacity of the stove, he made it all in brick. There is a hog in the attic, he didn’t redo it, just repaired it, as cold weather was approaching. The draft in the stove is excellent, due to the first stroke being lowered to the level of the vent, the floor became warmer. The bottom of the stove warms up wonderfully, and after closing the damper, the main array also warms up. BUT!... With the onset of stable cold weather (-10 and below), I was saddened to see dirty stains on the pipe. Having crawled into the attic, I saw that the entire pipe and the hog were damp, and ice had appeared from the bottom of the hog. We heat it every day (once). Who can advise?

Sergey from Tver

15.01.2011, 23:33

With the onset of stable cold weather (-10 and below), I was saddened to see dirty stains on the pipe. I crawled into the attic and saw that the entire pipe and the hog were damp, and ice had appeared from the bottom of the hog. We drown every day (once). Who would advise?

Insulate the hog and pipe - URSA two layers + foil (other options are possible).

16.01.2011, 01:35

Andre 114, the heat loss is too large near the channels of your furnace, you need to break through the burnout, making the shortest path for heating the pipe, in the partition between the first and last channels. Maybe the channels where narrowed, what turns. Is the pipe brick or iron? Channel height?

16.01.2011, 23:02

The height of the channels is about 20 cm, only the first, the lowest is 14 cm. But the draft is wonderful. I already guessed that the heat removal is too high, but I don’t know how to burn out between the first and last channels, the channels are horizontal. I think that in my case there is no insulation I can’t do without pipes, if this doesn’t help, I’ll remove the top one in the summer.

16.01.2011, 23:17

After condensation, the pipe will become overgrown with deposits, the brick will be saturated with condensation, something needs to be done before summer. Use a hacksaw with a sharp nose to cut out the bricks where the partition is supposed to be, take out a couple of bricks and make a burn there. I use a long chisel to break out the partition with a hammer. A turn in the channel on one side means the burnout must be done on the other side, it can even be done in all channels. I also did the insulation of the pipe, it only helped in non-freezing weather, but in cold weather it still gets wet at first, icicles, then it starts leaking into the house. That’s it. I am more convinced of the correctness of Victor Selivan’s theory about the need for burnouts.

17.01.2011, 00:05

Thank you all for your responses and advice, I’ll try to solve the problem using the “scientific” method. I’ll post back later if it helps.

Sergey from Tver

17.01.2011, 11:37

After condensation, the pipe will become overgrown with deposits, the brick will become saturated with condensation, something needs to be done before summer. Using a hacksaw with a sharp nose, cut out the bricks where the partition is supposed to be, take out a couple of bricks and make a burn there. I use a long chisel to break out the partition with a hammer. A turn in the channel on one side means the burnout must be done on the other side, it can even be done in all channels. I also did the insulation of the pipe, it only saved me in non-frost weather, but in cold weather it still gets wet at first, icicles, and then leaks into the house. I am becoming more and more convinced of the correctness of Victor Selivan’s theory about the need for burnouts.

The reasoning is absolutely correct, but in this case when the pipe and hog are cold, there is good draft, that is, there is no formation of cold air pockets. This suggests that the internal cross-sectional areas of the hog and chimney are overestimated. Most likely, the hog and the pipe are older than the existing stove, and were left after dismantling the old Russian stove - a typical case of the seventies of the last century, when instead of Russian stoves, or in addition to them, heating shields of various designs were often installed. In those days, you could see pipes and hogs wrapped in old sweatshirts. This was done to prevent the formation of condensation and its freezing in the brickwork. Otherwise, in the summer it was necessary to repair the hog and the pipe, since the tightness of the masonry was broken. Increasing the temperature of the flue gases gives a good effect at a normal calculated ratio of the furnace power and the dimensions of the pipe section. In this case, this will lead to increased consumption of firewood.
Therefore, in the current situation, it is better to make insulation. It is necessary to put foil under the insulation and on top, gluing it with heat-resistant tape, otherwise the insulation will get wet and the required effect will not be achieved. In the summer, of course, it is worthwhile (if possible) to burn out this stove, but do not forget to eliminate the hog and install a chimney corresponding to the power of the stove, preferably a “sandwich”.
And further. There is no theory by Victor Selivan about the need for burnouts.
Material from Wikipedia:
“Theory is a doctrine, a system of ideas or principles. It is a set of generalized provisions that form a science or its section. Theory acts as a form of synthetic knowledge, within the boundaries of which individual concepts, hypotheses and laws lose their former autonomy and become elements of an integral system.”

17.01.2011, 12:12

I have a book by V. Selivan, in all furnaces there are suctions between the channels, this is the main design principle of the author. Of course, he promotes his idea as zealously as some, but his furnaces work. As for the foil on the first layer of insulation, I will take this into account future Indeed, the size of the pipe matters, you are right about this, of course. And I do burnouts in winter without damage to the stove and warming up the house, I can manage it in one day.

18.01.2011, 00:53

I have a house with a residential semi-basement, in which there is also a stove, but we heat it only in severe frosts so that the floor is warm. The chimney from the lower stove is combined with an array of the upper one and also rises to the hog (the back wall of the firebox at the top of the stove is precisely formed by this chimney), it can be used as a burnout, i.e. punch a small gap through which some of the smoke will go directly into the hog?

18.01.2011, 01:00

18.01.2011, 01:07

I really didn’t think about it. I have a damper from the bottom stove at the top, okay, let’s think about it

14.12.2011, 00:04

Hello! I have a similar situation. We bought a house where no one lived for 10 years. In the summer, the stove maker moved the stove in the kitchen. It was an ordinary brick pipe of 2 bricks. In the fall, we began to lightly heat it. Problem No. 1 - it smokes slightly when starting the kindling, but the draft is good. Problem No. 2 - now they started heating regularly once a day for about 1.5 hours. The firewood was aspen and birch. After 2 weeks of heating, we noticed small wet spots on the pipe in the kitchen. We opened the pipe cleaning - there was a centimeter of water there. The water was clean. They rose into the attic - the whole pipe is stained. The pipe is plastered. It’s quite warm in the attic, and the weather here is still from 0 to +5. The attic is not insulated. I’m afraid what will happen in the cold? They started heating with a completely open vent. there is no water, but the pipe is damp and there are no drips. There is no summer valve in the slab, there is a shield with horizontal passages. What should I do? Is there any point in insulating the pipe?

The whole problem is the size of the pipe - very large for your stove. This is usually observed after replacing a Russian stove with a regular “Swedish” one (the stove is changed, but the pipe is forgotten). The simplest way out in this situation is to insert a “VULCAN” chimney (internal diameter 150 mm, external 250 mm) inside the existing pipe, and the hog, if any, must be well insulated. To install the chimney, do not forget to invite a normal stove builder. In the future, you should think about building a new furnace.

14.12.2011, 12:14

Sergey from Tver

14.12.2011, 12:52

There is a hog. It comes from the bed in the room and goes out into the same pipe as the stove. But it does not go through the attic, but into the room. Probably, then there is no point in insulating it? And the stove was completely disassembled and made new. On the same place and almost the same in shape as the previous one. I don’t know how much the internal structure has been changed. The shield reached the ceiling, now it’s not so high. I don’t know if the former owner had such problems - he died 8 years ago. Are the recommendations the same?

This meant a hog in the attic. In the current situation and the recommended option, it is better to start firing stoves from the kitchen. In the future, instead of the reversible sleeve for the “bed”, it is necessary to install a separate pipe (preferably a “sandwich”).
A stove with horizontal channels and no summer operation is an additional “headache” when lighting and servicing the stove.

Zhirnov Vladimir

17.12.2011, 00:15

Not everything will go straight; don’t get carried away with the width of the burn. It will be better to warm up, because in every mountain. the channel will receive an additional portion of the mountains. gases If you have the entrance to the shield and the exit from the shield to the pipe in different corners, punch boldly and wider. You will get a straight-through shield

Bibliographic description: Shirokova O.I., Zinatova M.Kh. Molecular physics in proverbs // Young scientist. 2015. No. 3. P. 134-136..06.2019).

“It’s not without reason that the proverb is said”

(Folk wisdom)

Proverbs and sayings are the embodiment of folk wisdom, the embodiment of the experience accumulated by humanity over the centuries. If you don’t know what to do in a given situation, it’s enough to turn to the wisdom of your ancestors, contained in proverbs and sayings, and time-tested.

A proverb is a short folk saying with edifying content, a folk aphorism. It conveys the meaning of a particular life situation through symbolic images and comparisons, plays an important role in our lives, many life situations can be explained with its help. Proverbs of the peoples of the world have much in common with natural differences reflecting historical, socio-economic, natural conditions, in which this or that nation was formed.

Often, proverbs vividly reflect physical phenomena. Moreover, proverbs can be compared with physical laws or mathematical formulas, because their short form contains rich content. They are our asset. They demonstrate the brilliant brevity of the people's language, the liveliness of conversational intonations and have long gained well-deserved fame.

But are they always true from the point of view of the laws of molecular physics? I tried to give answers to these questions in my article. Now let's look at proverbs that talk about thermal phenomena. Let's try to explain the physical meaning of certain processes described in proverbs. Here are some of them.

 Flint on flint- spark(Russian). Which is understandable: ignition occurs due to an increase in internal energy as a result of work done against friction forces.

 The smoke melts inair (Russian). Smoke particles participate in Brownian motion and hit each other. The volume occupied by the smoke increases, and the density of the smoke decreases.

 You can’t heat the sea with a nail (awl) (Russian). A nail (like an awl) has a small mass, and the metal from which it is made has a relatively low specific heat capacity. Therefore, the amount of heat that a nail can give off is small, and it cannot heat a large mass of water.

 A lot of snow- a lot of bread (Russian). The snow is deep- the year is good (Russian).Snow- a blanket for wheat: the thicker it is, the better it sleeps (Chinese). Snow has very poor thermal conductivity, since between its components there is air, which is a poor conductor of heat, and the thicker the snow, the worse it conducts heat. Therefore, snow can be compared to a blanket that protects winter crops from freezing. In addition, in the spring, when more snow melts, more moisture enters the ground, which has a beneficial effect on the germination of grain crops.

 The sun is hotter when there are no clouds (Mongolian). Clouds act as a kind of “screen”, preventing direct sunlight from heating the earth more strongly.

 Water has a flexible back (Finnish). Water arrives in different states of aggregation; in the liquid state it has fluidity.

 Winter- not summer, inwearing seven fur coats(Russian). In winter, the ambient temperature is lower than that of humans. To keep warm, a person puts on a fur coat - fur clothing. Since fur has poor thermal conductivity (due to the presence of air between the hairs), the heat of the human body is not transferred to the surrounding air.

 Fly in the ointmentbarrel of honey (Russian). Small bug, but stinky(Russian).A vegetable shop doesn't need a sign. Diffusion (as a physical and chemical process) is the mutual penetration of molecules of one substance into the spaces between the molecules of another. In this case, honey and tar diffuse. Tar is a resinous liquid substance with a persistent unpleasant odor. Therefore, even its small mass will spoil the product.

 Make hay while the sun shines (English). Evaporation rates are higher at higher temperatures.

 Sliced onions smell andburns the eyes more (Mongolian). Diffusion occurs more intensely around a chopped onion than around an onion enclosed in a peel.

 On a bag ofsalt andsalted rope (Korean). The salt diffuses through the bag.

 Evil andgood as water andbutter: they cannot mix (Mongolian). The density of oil is less than the density of water, so it floats in water. These liquids do not mix because they have different densities.

 Absorbs like a sponge(Russian). In the old days, sea sponges were used instead of rags. They are penetrated by many thin vessels and after processing in boiling water, their capillary passages are easily filled with liquid. Such sponges are able to absorb quite a large amount of water.

 Like withgoose water (Russian). The feathers of goose and other waterfowl are covered with a thin layer of fat, which is secreted by subcutaneous glands. Fat is not wetted by water. The bird, coming out of the water, shakes itself and turns out to be dry.

 The metal is cast well if it boils for a long time (Russian). Increasing temperature solids the kinetic energy of their particles increases: they begin to oscillate at a higher speed. Destruction occurs, the lattice disintegrates (long-range order turns into short-range order), and the crystal begins to melt, i.e., the substance begins to transform into a liquid state.

 Strike while the iron is hot(Russian). An increase in temperature sharply increases the plastic properties of materials, so that many metals can be forged only in a very heated form. It is quite easy to give hot metals the required shape.

 It’s easy to rake in the heat with someone else’s hands(Russian).“Heat” - burning coals that burn your hands. Raking them out of the oven was not an easy task for the housewife: it would have been simpler and easier for her to do it “with the wrong hands”, without the risk of getting burned.

 Friendship is like glass, you'll break it- you can’t put it together (Russian).Cut off a piece ofyou can't put bread on it. You'll chop it off- you won’t put it down, you’ll say- don't turn it back(Russian). Each molecule attracts all its neighbors and is itself attracted by them. The mutual attraction between molecules becomes noticeable only when they are very close to each other. At a distance greater than the size of the molecules themselves, the attraction weakens. However, the fragments (pieces of bread) cannot be healed, even by pressing them tightly. Due to the irregularities, it is not possible to bring them closer to the distance at which the intermolecular attraction of molecules acts.

 Do not pour oil on the fire. Do not add oil tofire. Fill the fire with oil- just turn up the fire(Russian). Hot oil begins to smoke due to the fact that at this moment unwanted chemical changes begin.

 Frozen as if at the bottom of the sea (Russian). This is explained by the fact that it is always cold at the bottom of the sea, since the sun’s rays do not warm up the layers of water: thermal, infrared rays are absorbed by almost the entire water surface. In addition, water has a relatively low thermal conductivity.

Dear reader, try to explain the physical meaning of some Russian proverbs:

- The sun warms the universe.

- Don’t grab hot iron.

- The red sun in the white light warms the black earth.

- Which barn has snow on it, buy bread from it.

- There is no smoke without fire.

- And damp wood catches fire.

Work on this topic introduced me to the world of living nature, which is sensitive to environmental changes. It opened my eyes again to the diversity of sources of information about the nature of my native land, living and beautiful, familiar from childhood, but lost in the depths of memory. She returned to the world of folk proverbs and sayings based on people’s observation. I came to this conclusion: folk proverbs and sayings are not a set of laws. They not only express ethical standards, but are also closely related to physics.

Literature:

Ozhegov S.I. Dictionary of the Russian language: OK.53000 words - Moscow, Onyx Publishing House LLC, 2005.-1200 pp.
Tikhomirova S. A. Physics in proverbs and sayings [text] - Moscow: Education, 1993.- 47 p.

YARTSEVSKY INDUSTRIAL TECHNICAL SCHOOL

EXTRA-CLASSROOM ACTIVITY:

"PHYSICS ON THE WALK"

DEVELOPED: Physics teacher

Prokhorenkova O.A.

Purpose of the event: Show the connection between physics and various natural phenomena that answers to momentary questions that arise in life, everyday life, in nature, etc., can only be given on the basis of knowledge of physical phenomena and patterns;

“Include” students in active mental work during the hike;

Give an intellectual touch tourist trips, going out into nature, filling rest stops, hours of rest and outdoor games interesting tasks related to physics;

Teach to see physics in the world around us;

Development of a sense of camaraderie, mutual assistance, competition, responsibility, cognitive interest;

Fostering a culture of communication, rules of conduct while hiking, environmental education.

Objectives of the event: To repeat the basic physical concepts, formulas, laws and phenomena in their direct manifestation in nature, to show the organic connection between theory and practice.

Methods: Verbal, visual, practical, active, stimulating, encouraging.

Material and technical equipment: Camping equipment, inventory, improvised means, dishes, prizes, paper, pens, calculator.

Literature:

M. E. Tulchinsky “Qualitative tasks in physics.” Moscow, Dedication, 1972.

S. A. Tikhomirova “Physics in proverbs, riddles, and fairy tales”, Moscow, School Press, 2002.

S. A. Tikhomirova " Didactic materials in Physics", Moscow, School Press", 2003.

V. I. Elikin, L. D. Garmash “Physics and astronomy on a hike and in nature”, Moscow, School Press, 2003.

Journals “Physics at School” No. 3 1997, No. 6 2001.

Many years of tourism have shown that this is a huge, effective and still little-used source of opportunities for understanding the world around us and educating people. In the forest, by the river, by the fire, nature imperiously invades the life of a tourist, into his soul and heart, subordinating it to its laws. And everyone, first intuitively and then consciously, comes to the conclusion that knowledge of the laws of nature is necessary.

A hike is a space for observations, active mental work, it is a space for communication, organizing competitions, quizzes, setting up experiments and experiments.

Work experience allows us to assert that on hikes, students learn and apply the laws of physics more effectively than at their desks, since they clearly feel the “action” of these laws of nature on themselves.

The content of this event is designed for a two-day hike with one overnight stay. The tourist group is divided into three teams, each of which functions as a single unit throughout the entire trip, that is, not only takes part in competitions, but also participates in all everyday affairs of the camp. Thus, the winning team is determined at the end of the campaign, where the team’s effective participation in all stages is taken into account.

Intellectual competitions and outdoor games must be rationally alternated in order to change types of activities.

In order for the event to be completed, it is recommended that students at the end of the hike be asked to complete homework optionally.

Explanations for the event

Physics through the eyes of a tourist

It is dangerous for a tourist to stay in wet clothes and wet shoes for a long time: you can easily catch a cold. Why?

Explain why, if our hands are frozen in the cold, we blow on them to warm ourselves up? And sometimes we blow on them in the summer. Why and what does this give?

When leaving a person's lungs, water vapor is always released along with air. Why do we see it only in winter or very cold autumn?

Why shouldn't tourists leave water in a glass bottle outside in winter?

What is the temperature of the puddle in which the ice floats?

Place your palms so that they are illuminated by the sun's rays: remember the sensations. Now wet your palms with water and again expose them to the sun. Compare your feelings. How do you explain them?

You see a tractor in the distance. How do you determine whether it is moving or standing still?

Are there “points” on the body of a walking tourist (name them) that move: A) progressively. B) rotationally. B) oscillatory.

How, when approaching a railway track, can you find out about the approaching train in a simple way based on knowledge of physics?

At what time of year do electrical wires on poles along the road sag more, why?

Why did an experienced tourist take a white Panama hat on a summer hike?

Why is it so much harder to walk uphill on a road than downhill?

Why is it impossible to cook meat high in the mountains even in boiling water?

Why does it hurt to walk barefoot on mown grass?

Why does fog form first in the lowlands in a meadow after sunset?

How can we explain the spread of the smells of meadow flowers, mown grass, and smoke in the calm air?

Why does a person coming out of the water after swimming feel cold, and this feeling is especially strong in windy weather?

Approaching the river, one of the tourists shouted loudly. After 5 s, he heard an echo from the opposite wooded bank. What is the distance to it? (Sound speed is assumed to be 331 m/s)

Tourists left their poorly inflated volleyball on the beach. And he lay for some time under the rays of the sun. At the same time, he swelled up as if he had been pumped up. Explain what happened.

Why does the sand on the beach get hotter than the water on a hot sunny day? Is it colder than water at night?

On a hot summer sunny day, the travelers decided to take a break. Where is it better to sit down to rest: on a rock or on the ground? Why?

Why is it difficult to cut wood directly on the ground?

Why is it so important to sharpen them well when working with an ax and knife?

With an axe, which handle, long or short, is easier to chop wood?

How to explain the action of a pipette? Syringe?

How to explain the blood-sucking effect of the bandage with which the attendants tied a cut finger?

The attendants need to bring dry wood for the fire. By what physical characteristics can you distinguish dry firewood from wet firewood?

Where is the best place to string a line to dry washed clothes?

What kind of water, warm or cold, is better to drink with the medicine so that it is absorbed faster?

In what water, hot or cold, is it better to soak peas for cooking soup so that they swell faster?

Does the water in the “tubes” of cooking pasta boil?

How can we explain that if you cook porridge, for example pearl barley, over high heat in a pot covered with a lid, then when the lid is removed, the inside is “strewn” with stuck grains?

Why does butter foam when you melt it in a frying pan?

To prepare crackers, bread is cut into thin slices or cubes. Why?

What role do salt and sugar play in canning?

Explain in physical language what happens when we “strike” a match on a box. Why does the match light up? A match can be lit by touching its head to the fire. Are the ways of changing the energy of the match the same in both cases?

The heat of combustion of birch firewood is greater than that of pine wood. How do you understand this expression?

Why does water extinguish the fire?

In which pot, open or closed, does water boil faster?

Hot tea was left in a pot by the fire. To what temperature will it cool down if they stop adding wood to the fire?

Which spoon is better to eat with: wooden, steel or aluminum?

Which soup will cool faster: fatty or lean? Why?

The tourist leaves nothing on his plate; he picks up the sauce and gravy with bread crumbs. Why does he succeed?

For lunch they distributed crackers instead of bread. And this always happens on a long hike. Why do tourists take crackers instead of bread? What physical phenomena underlie the preparation of crackers from bread?

Why do dew and fog form? Why is there heavy dew after a hot day?

What force causes raindrops to move towards the ground?

Caught in the rain, the tourists got pretty wet and hung their wet clothes on clotheslines. But they were not dry by morning. Why?

Where should you wait out a thunderstorm if it overtakes you: in the forest, on a mountain or on a hill, while swimming in a pond?

Why does a mosquito squeak and a fly buzz?

How can you determine when you see a bee flying: is it flying after prey or returning to the hive with it?

Why do many animals sleep curled up in cold weather?

Why do water striders calmly move across the surface of a reservoir?

Explain the meaning of the saying “Water is off a duck’s back” and the expression “Wet chicken.”

What physical processes are involved in fish respiration?

Why does a dog stick out its tongue in extreme heat?

Why do they think that if the stars are clearly visible in the sky, then the night will be cold?

Explain the sayings from the point of view of physics:

The dry spoon hurts my mouth.

It goes like clockwork.

It creaks like an unoiled cart.

Slippery like burbot.

Mow your hair while there is dew.

Look at all the flora and fauna around you and choose from what you see examples of different types of mechanical movement.

Watch the flight of birds: what do they “do” with their paws? How to explain this?

Look closely at how a caterpillar crawls along a leaf of a tree. Now explain the method of its movement from the position of physics.

Bend a tree branch. What deformations do you think occurred on its outer and inner surfaces?

Look at the aspen leaf. What kind of movement are they making and why are they shaking?

Listen to the noise of the trees. Why are they making noise? What is the nature of these sounds.

Puzzles

From prison one hundred sisters

Released into the open

They take them carefully

Rubbing my head against the wall,

They strike deftly once and twice -

Your head will light up. ………(Matches)

We put firewood in it -

Then he highlights

Lots of light and warmth.

And the food is being prepared. ……….(Bonfire)

What is not visible from the fire, but everyone needs?……(Warmth)

Sat down in the heat

Steam from the nose. ………..(Kettle)

Little scoop

Dear friend to everyone,

They take it three times a day,

Then they put it back in place. ……..(Spoon)

I'm small and remote.

It's worth looking at me

I'll show you the way right away. ……….(Compos)

You are behind her, she is from you,

You are from her, she is behind you. ……(Shadow)

Who, without studying, speaks all languages? …….(Echo)

It pours into it, it pours out of it,

She trudges along the ground on her own. ……..(River)

It curls around the nose, but is not easy to handle. ……(Smell)

Warms in winter, smolders in spring,

It dies in the summer and comes back to life in the fall. …….(Snow)

If you put it in the oven, it will get wet,

If you put it in water, it will dry out. …….(Candle)

In the evening it flies to the ground,

Night remains on earth,

In the morning it flies away again. …..(Dew)

Come on, grab a handful of her -

Can't hold it in a handful. …….(Water)

Who doesn't see me?

But everyone hears

And everyone can see my companion,

But no one hears. ……(Thunder, lightning)

On the street there is a shirt, but in the hut there are sleeves. ….(Sun rays)

When is the sky lower than the earth? ……(When reflected in a body of water)

A painted yoke hung across the river. ….(Rainbow)

Without a head, but with horns. …..(Month)

What is visible only at night? ……(Stars)

Fireflies in the blue sky

You can't reach them with your hands,

And one big firefly,

Curved like a worm. ……(Stars, month)

Proverbs

What physical phenomenon (concept, law) is referred to in the proverb?

What is its physical meaning?

Is the proverb true from a physics point of view?

What is its everyday meaning?

Mechanics

Run if you have to, but don’t fall on your face.

You can’t move a stone alone, but with an artel you can lift mountains.

Things went like clockwork.

The plow shines from work.

They pull ten uphill, and push one downhill.

A large tail is difficult to wave.

You can't get away on one wheel.

You can't hammer a nail with a light hammer.

Hydro-aerostatics (dynamics)

Even a small pebble will not float if it falls into the water.

Water always flows down, smoke always rises up.

Only bubbles float well.

The wind blows, winnows the grain.

Beware of the quiet dog and the quiet water.

Oscillations and waves

Just as you don’t swing a swing, the time will come to stop.

Which string has broken can be heard by the sound.

Whatever you click in the forest, that’s how it will respond.

An empty barrel makes a lot of noise.

You can't cover your ears from strong thunder.

If you don't beat the drum, it won't make a sound.

A bat can see in the dark.

Molecular physics

A fly in the ointment.

Friendship is like glass: if you break it, you won’t be able to put it back together.

There is a salty rope on the bag of salt.

He ran towards the smell of meat, thought it was pilaf, but he came running and looked: they were branding donkeys.

Heat and work

Snow is a blanket for wheat.

Wind is a helper to fire.

If the poker is long, you won't burn your hands.

No matter how hot the water is, it will not burn down the house.

I would ask the goose if his feet are cold.

Don’t try to eat hot porridge from the middle, but take it calmly along the edge.

MCT of vapors, liquids and solids

You recognize the approach of winter by the frost, the approach of summer by the rain.

The salt marsh does not turn green, the fool does not grow wiser.

The fog eats up the snow.

Water has a flexible back.

Flows like tar in the cold.

You can't paint a picture on water.

Evil and good are like water and oil: they cannot mix.

Talk to him about carrying water in a sieve.

The less a tree bends, the easier it breaks.

From the young, like from wax: you can mold whatever you want.

A roost with too many chickens will collapse.

Team competition

Packing the backpack

“Is your backpack friend or foe?”

Packing a backpack is a “fusion” of science and art. The laid backpack should be flat and high in shape, the side adjacent to the back should follow the shape of the back as accurately as possible, because in this case the pressure of the backpack on the back will be significantly less due to greater support (P= F/ S).

For the same reason, the backpack straps should be wide, and it is advisable to have a semi-rigid belt at waist level. The center of gravity of the backpack should be as close as possible to the back at the level of the shoulder blades, that is, as close as possible to the vertical line passing through the biological center of gravity of a person.

When packing a backpack, heavy items should be placed as close to the back as possible, and light equipment should be placed as far away from it as possible.

Campfire

It's always nice to sit by the fire, the fire of which is conducive to conversation. You can talk about anything, including the phenomena that we learned about in physics lessons.

Lighting a fire is also a science. You need to collect suitable firewood, stack it correctly and finally light it using minimal amount matches. And if the matches are damp, or they were completely forgotten to take, what to do in this situation? How can you make fire?

Using solar radiation and a magnifying glass, that is, a plano-convex lens. The lens must be positioned so that some of the sun's rays pass through it and focus on highly flammable material: paper, moss, hay, etc.

(This method is based on the ability of a collecting lens to focus rays at one point and concentrate the radiation energy in it.)

By striking a piece of metal against the silicon, the resulting spark is directed at a highly flammable material.

Fire is created by rubbing a dry stick on wood.

(2 and 3 methods are based on the transition mechanical work into warmth.)

3. Meals during the hike

The life and activity of the human body is associated with continuous expenditure of energy. These costs consist of the costs of basic metabolism (that is, maintaining the existence and functioning of the body), work and rest.

Any energy costs and ordinary life and require restoration during the hike. The body receives the required amount of energy as a result of eating food and processing the organic substances it contains: proteins, fats, carbohydrates. Food is a kind of fuel that supports the vital activity and functioning of the human body. But different foods have different energy values, just as different fuels have different calorific values: that is, when burned in the body, 100 g of different foods release different amounts of energy.

Dependence of energy costs on the type of tourism and the category of difficulty of the hike (per 1 person per day)

Type of tourism

Difficulty factor
			Lowest		Average			Higher
			1		2		3	4			5
Pedestrian			12 990		14 246		15 503	17 180			18 855
Water	0,8 – 0,9		10 391		11 397		12 151	15 461	16 970
Ski		15 587		17 095		18 436		20 615		22 626
Mountain		16 886		18 520		20 154		22 333		24 512

Energy consumption at various types activity and rest (per 1 kg of body weight)

Cost type

Amount of energy consumption (kJ)
Walking on a flat road at a speed: 4.2 km/h 6 km/h 8 km/h	13,4 18,85 41,9
Walking uphill on a slope at a speed of: 2 km/h	26,9
Running on a flat road at a speed of: 9 km/h	37,7
Swimming speed: 10 m/min	2,57
Dream
Rest lying down without sleep

The main source of energy in food is carbohydrates. They provide up to 70-75% of the required energy, the share of proteins and fats is 25-30%. They are used primarily to build new cells and produce enzymes. In food products, fats, proteins and carbohydrates should be in a ratio of 1:1:4.

Energy value and composition of basic food products

The product's name

Digestible part per 100 g of product in grams

Energy value (kJ)

Proteins fats carbohydrates

Rye bread

Wheat bread

Crackers

Bread products

5 1 42

7 0,4 45

10 1 69

12 15 58

1425

1777

Condensed milk

Processed cheese

Hard cheese

Dairy products

7 8 55

19 18 2

22 20 3

1385

1064

1223

Butter

Sunflower oil

Pork lard

Egg

Fats, eggs

0,8 78 0,6

2 82

12 11 0,5

3071

3696

3524

Semi-smoked sausage

Sausages

Canned pork

Canned beef

Meat products

14 35

12 14 6

13 28 0,3

16 12 0,4

1550

1320

Sprats in oil

Pike in tomato

Fish products

16 31 0,7

10 4 4

1483

Buckwheat

Semolina

Oat groats

Pearl barley

Rice cereal

Pasta

Cereals, pasta

9 2 63

10 0,7 70

9 6 60

6 1 66

7 1 73

9 1 71

1328

1400

1408

1300

1499

1408

Sugar

Caramel candies

Chocolate

Jam

Sweet

5 27 62

0,3 62

1676

1383

2154

1048

Carrot

Beet

Potato

Vegetables

13 55

7 54

6 72

1131

1039

1320

The body requires compliance with energy balance: equality of energy expenditure and the amount of energy supplied to it from food. Knowing the energy consumption on a particular section of the route, you can use the tables below to plan your diet: its energy value (calorie content, composition and weight)

How to plan meals on a hike?

First of all, an energy balance equation is drawn up.

It is taken into account that normal meals should be hot and three times a day, that is, consist of breakfast, lunch and dinner.

Between breakfast and lunch, after about 3 hours, you can have a “snack”, the energy value of which should be 10% of the daily diet.

Now, knowing how to properly plan meals on a hike, you need to create a daily diet according to the following scheme: 30% + 10% + 20%.

Your travel mug

When camping, every little thing is important, like a mug. How can a tourist manage without it? But which mug should you take with you on a hike? Of course, durable and light. Everyone knows that materials such as glass are fragile, metals are stronger, and plastics are lighter. Which mug should I take? What needs to be done to prevent an aluminum mug from burning your hands? How to make an unbreakable thermos mug?

Who will throw the pebble higher?

The pebbles should be approximately equal in mass and volume. How will the judge determine whose pebble has risen to the greatest height?

Determine the average speed of the ant

Walk so that your path and movement are 2 each, but lie on the same line.

Take out the potato

In a mug filled with water on top, there is a potato at the bottom. Get her out. You cannot tilt or move the mug, and you cannot use foreign objects either.

Thermal conductivity

Prove, using available materials, that thermal conductivity of thermal conductivity is poor, while that of aluminum is good.

Prepare jelly

You have a 4 liter pot and a 10 liter bucket. Using these items, how can you pour 2 liters of water into a kettle to prepare jelly?

Keep warm

Egg

How can you tell if an egg is raw or boiled without breaking the shell? Why?

Drown the bottle

An empty plastic bottle must be drowned in water. How to do it?

Make a filter

Make a filter for water purification from natural materials: pebbles or pebbles of different sizes or sand, an empty plastic bottle, gauze. Demonstrate it in action.

Make a beaker

Using a half-liter jar and a 200 gram glass, make a beaker from a plastic bottle with a division value of 100 g.

MOU-SOSH village. Stolypino

Teacher:

Lesson on the topic: "EVAPORATION"

1. Contents of the survey. (front)

What is meant by internal energy? Ways to change internal energy? Quantity of heat? In what states of aggregation can the same substance exist? What process is shown in the picture? What process is called melting? How does the internal energy change when a substance moves from solid state into liquid? Can you melt silver in an aluminum pan? (Answer: No, because the melting point of silver is higher than the melting point of aluminum.) Physical meaning of specific heat of fusion. Let's solve the riddle:

“It flowed, flowed, and then fell under the glass” (Answer: water and ice)

What process are we seeing here? (Answer: crystallization) What process is called hardening? At what temperature does the crystallization process occur? Explain the expression: “A worn-out fur coat does not keep you warm.” What will cool the water more: a piece of ice at 00C or the same mass of water at 00C? (Answer: Ice, because it will melt first and take away some of the heat.) The poet said: “Oh drop!”

“...She lived and flowed on the glass,

And the drop became a motionless piece of ice,

And the world has become less warm..."

Is the poet right? (Answer: No, t. we are talking about the process of crystallization, which is accompanied by the release of heat.)

On the task board:

TASK #1

Melting a copper ingot weighing 2 kg required 420 kJ of energy. Using these data, determine the specific heat of fusion of copper.

Given: Solution.

m =2 kg Q =E =m ·λ → λ=Q /m

E = 420 kJ=420000 J [λ ]=J/kg

λ =420000/2=210000=2.1 ·105 (J/kg)

λ=? Answer: 2.1 105 J/kg

Additional: ? Which of the two observers is colder during ice drift? (Answer: It is colder for the observer near the river, since ice absorbs a large amount of heat when melting)

? In which carriage are perishable products transported? (Answer: In cars painted white, since such a car heats up less)

TASK #2

What amount of heat is required to convert a piece of ice weighing 100 g, taken at a temperature of -2ºC, into water at a temperature of 0ºC?

Given: Solution.

m =100 g=0.1 kg 1. How much heat is needed to heat ice to

t 1=-2ºС melting point? Q 1=cm (t 2-t 1)

t 2=0ºС Q 1=2100 J/(ºС·kg) 0.1 kg(0ºС-(-2ºС))=420(J)

λ =3.4·105 J/kg 2. How much heat was used to melt the ice? Q 2=m λ

c = 2100 J/(ºС kg) Q 2 = 0.1 kg 3.4 105 J/kg = 3.4 104 J

3. Find the total amount of heat. Q = Q 1+Q 2

Q =? Q = 420+34000=34420=34.42 (kJ)

Answer: 34.42 kJ.

Additional:? Will the air temperature change if the weather conditions in the upper picture become the same as in the lower one, i.e. it snows? (Answer: The air temperature will rise where there has been snow. The formation of snow crystals is associated with the release of heat of fusion)

CROSSWORD " THERMALPHENOMENA"

F -8

The process of transferring energy without doing work.

The process of turning a liquid into a solid.

A physical quantity important for thermal phenomena.

Temperature drop.

The process of turning a solid into a liquid.

What does the physical body consist of?

One of the aggregate states of matter.

Q=с·?(t2-t1)

Type of solid state of water.

Type of gaseous state of water.

F.I. __________________________________

Class ______________________

TASK #3

Solve the problem graphically, indicate the processes and formulas for calculation.

How much heat must be expended to melt a piece of tin weighing 2 kg, taken at a temperature of 32ºC and the resulting melt heated to 300ºC?

2 . Presentation of new material.

Let's start a story about warmth,

Let's remember everything and summarize now.

Energy! Work to the boil!

May laziness evaporate!

We won’t let our brains melt

We train them until exhaustion!

We will show diligence in learning,

Scientific ideas seeing charm!

We can overcome any challenge

And we can always help a friend!

But how difficult life can be

With that lady who is called: “Warmth”!

Topic of our lesson: "Evaporation and Condensation".

Why do puddles left after rain, freshly cut hay lying in the meadows, and washed clothes hanging in the sun quickly dry up on a clear summer day? Where does the water disappear to? We will try to get answers to these and other questions during the lesson.

First, let's remember the basic principles of molecular kinetic theory:

1. All bodies are made of molecules;

2. They are in continuous and chaotic movement;

3. Molecules interact with forces of attraction and repulsion.

What are the physical states of matter? We learned about the transition of a substance from a liquid to a solid state and vice versa.

In liquids, molecules move at different speeds. If a molecule with an energy greater than the average kinetic energy approaches the surface of the liquid, then it, overcoming the attraction of neighboring molecules, will fly out of the liquid. The combination of such escaping molecules forms steam. Evaporation is the formation of steam on the surface of a liquid. It occurs at any temperature.

Give examples of evaporation.

Evaporation is the phenomenon of the transition of molecules from liquid to vapor.

What determines the rate of evaporation of liquid? Let's do the following experiment. Place droplets of water, oil and alcohol on a piece of paper. Watch which liquid evaporates first.

The rate of evaporation depends on the type of liquid.

Give examples.

If we pour the same amount of water into a glass and a saucer, where will the water evaporate faster? Absolutely right in the saucer.

The rate of evaporation depends on the surface area.

You can do this experiment at home.

Give examples.

background:yellow">The rate of evaporation depends on the presence of wind.

Give examples.

When will laundry dry faster on a sunny or cloudy day? (drawing). Evaporation occurs at any temperature, but with increasing temperature the rate of evaporation increases.

The rate of evaporation depends on temperature.

Give examples.

It is interesting to note that not only liquids evaporate, but also solids. (picture) For example, the evaporation of ice can explain the fact that wet laundry dries out in the cold (If wet laundry is hung out in the cold, it will first freeze (water will turn into ice), and after a while it will dry out, therefore the ice will evaporate.) Evaporation of naphthalene , can be detected by smell. The evaporation of solids is also explained by the presence of fast particles in them that are able to overcome molecular forces.

So, what factors determine the rate of evaporation?

Why does dew fall on a summer evening when it gets cool?

Vapor molecules located above the liquid close to its surface return to the liquid. The evaporation process is always accompanied by a condensation process.

In an open vessel, evaporation occurs faster than condensation, so the amount of liquid in the vessel decreases. If the vessel is closed, then both evaporation and condensation will continue, but after some time the number of molecules leaving the liquid will become equal to the number of molecules returning to it. They say that the liquid-vapor system reaches equilibrium.

The space above the liquid closed in the vessel is filled with steam. Such vapor in equilibrium with a liquid is called saturated vapor. If the vessel is opened, some of the steam escapes into environment, steam becomes unsaturated, again the number of molecules leaving the liquid becomes greater than the number of vapor molecules returning back.

? Do you think the temperatures of the air in the classroom and the water at “room” temperature are different? (after listening to the students’ answers, we make measurements that show that the water temperature is slightly lower than the air temperature.)

? Why do evaporating liquids cool?

font-size:24.0pt">? Coming out of the river after swimming, you feel cool, especially in windy weather. Why? (picture)

3. Consolidation of what has been learned in the lesson.

Evaporation is the most easily controlled method of reducing internal energy. Any conditions that impede evaporation disrupt the regulation of heat transfer from the body. Thus, leather, rubber, oilcloth, and synthetic clothing make it difficult to regulate body temperature.

Sweating plays an important role in the thermoregulation of the body; it ensures the constancy of the body temperature of a person or animal. Due to the evaporation of sweat, internal energy decreases, thanks to which the body cools.

Evaporation plays a big role in plant life. For example, sunflower or corn evaporates up to 200 kg of water in one growing season!

font-size: 24.0pt">? (drawing) Why does a dog stick out its tongue when it's hot?

font-size: 24.0pt">? Why can a camel go without water for a long time? / A camel can go without drinking for 2 weeks; it uses water very sparingly. A camel hardly sweats even in 40-degree heat. His body is covered with dense fur, which protects him from overheating and moisture evaporation. Never opens his mouth: after all, a lot of water evaporates from the mucous membrane of the oral cavity)

font-size: 24.0pt">? Why in the south is drinking water kept in unglazed clay jugs?

L.886. Why does grass clippings dry out faster in windy weather than in calm weather?

L.891. Why is a horse sweating after riding covered in a blanket in the cold?

L. 892. Wet wood burns worse than dry wood. Why?

? At what time of year will a puddle evaporate faster after rain in hot summer or cold late autumn? (drawing)

? Why are some semi-finished products, vegetables and fruits in stores packed in plastic or plastic bags?

4.D/z:§16,17, stubbornly).

Physics and folk signs about the weather

It is always important for a person to know what the weather will be like, since it affects well-being and activity. Observing nature in bad weather, on a sunny day, at dusk, at night, people noted characteristic signs that preceded certain weather changes. This is how numerous signs appeared - witnesses of people's observation, ingenuity, and wisdom.

“Weather” signs are varied. Some notice the behavior of people and animals, others are associated with various physical phenomena, and others are associated with religious beliefs.

Let's try to explain some of the folk signs from the point of view physical processes described in them.

Atmospheric air is the most important factor in the existence of living organisms, since it contains oxygen necessary for plants and animals. The surface layer of air contains (by volume) 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.03% carbon dioxide; less than 0.01% consists of helium, neon, krypton, hydrogen, xenon, ozone and radon combined. In addition to these gases, the air always contains water vapor, the amount of which, depending on temperature, is 0.01-4% (by volume). Air creates atmospheric pressure. It exerts pressure on the surface of the Earth and all objects and living beings located on it.

Air pressure at sea level at a temperature of 0°C corresponds to the pressure of a mercury column with a height of 760 mm - this value is considered to be normal barometric atmospheric pressure. Fluctuations in atmospheric pressure cause significant changes in weather.

Barometric pressure is closely related to air humidity. It is no coincidence that most of the simplest folk instruments - weather predictors - are based on determining fluctuations in air humidity. This is due to the fact that the density of water vapor relative to the density of air, taken as a unit, is 0.623. Therefore, humid air is lighter than dry air, and the atmospheric pressure in it drops. When the pressure decreases, the air becomes more humid, clouds form from water vapor and precipitation can be expected.

Air humidity. Changes in weather are largely due to changes in air humidity. It is known that smoke from chimneys or from a fire rises upward in clear, dry weather, and before wet weather, with an increase in the humidity of the ground layer of the atmosphere, it spreads along the ground and sinks down. In winter, when the air is dry and before frost, the wood in the stove burns brightly and burns out quickly. A dull pale flame, incomplete combustion of fuel, the formation of soot falling back from the chimney into the fire, weak draft are signs of high air humidity, the onset of bad weather in summer, and thaw in winter.

Fog, dew, frost. In spring, summer and autumn, after sunset, in calm weather, due to the cooling of the air, a continuous “blanket” of vaporous moisture in the form of fog often rises above the heated surface of the earth. From this natural phenomenon, one can also determine the nature of the upcoming weather. There are signs among the people , that “if the fog rises upward in the morning, expect rain, and if it settles to the ground, the weather will be dry”, “fog that disappears after sunrise portends good weather.” Night and morning fogs in the valleys, disappearing after sunrise, among shepherds of mountainous regions they are considered harbingers of good weather.In the summer, heavy dew foretells clear weather without rain.

Light phenomena. The nature of the weather can be judged by the color of the dawn at sunrise and sunset. The color of dawn depends on the content of water vapor and dust in the air. Air, highly saturated with moisture, predominantly transmits red rays, so a bright red evening dawn foreshadows inclement windy weather. A bright orange sky at sunset means strong winds. The intense bright yellow, golden and pink colors of the evening dawn indicate low moisture content and a large amount of dust in the air, which indicates upcoming dry, windy weather. The morning dawn is red in summer - a sign of rain, and in winter - a blizzard. “If the sun sets with a red dawn and rises with a bright one, it will be a bright and clear day.”

The approach of rainy, windy weather and thunderstorms can also be determined by the twinkling of stars, which occurs when warm and cold layers of the atmosphere mix, as well as when it contains a large amount of water vapor or ice crystals. In this case, a thin beam of rays coming from the star, passing through inhomogeneous layers of air, is either scattered or compressed. Because of this, the eyes perceive an unequal amount of rays, and the star appears either bright or dim. In a “calm” atmosphere, the straightness of the propagation of light is not disturbed and the stars do not twinkle. According to popular wisdom, “stars play in winter - towards blizzards, frost, snow, and in summer - towards rain”, “stars jump towards cold”.

The twinkling of stars usually begins 2-3 days before the rain. When thin clouds appear, distant stars become faintly visible, and nearby stars blur and increase in size. When there are high clouds, many stars are not visible, which is why people say: “When the stars begin to hide, it will soon rain,” “There are few stars in the sky - this means cloudy weather.”
These wise folk observations show that worsening weather is associated with an increase in the amount of water vapor in the air, i.e. humidity. Another folk sign says: “If a voice is heard far in a field, then it will rain.” What could this be connected with? How to explain this phenomenon?
In this case, people connected sound phenomena and an increase in air humidity! It turns out that as humidity increases, air density increases, and therefore the ability to conduct sound!

Worsening weather is usually accompanied by a drop in atmospheric pressure. As you know, the phenomenon of boiling is also somewhat dependent on atmospheric pressure: the lower the atmospheric pressure, the lower the boiling point of the liquid, the faster it boils! This phenomenon is also reflected in folk superstitions: “Pots easily boil over the edge - a sign of bad weather.” We are, of course, talking about boiling milk; at low pressure it “runs away” faster than usual.

The upcoming weather can be judged by the movement of clouds and their appearance, the direction and strength of the wind, the color of the dawn, and the optical effects around the celestial bodies - the Moon and the Sun.

Thus, a red dawn indicates the presence of a large amount of steam in the atmosphere, which will certainly lead to increased cloudiness and worsening weather.
Crimson dawns - to the winds.

The arrival of a thunderstorm can be determined even several days in advance by the sky, where thin transparent stripes of cirrus clouds begin to appear high up - a sure sign of loud thunderstorms.

The sun before a thunderstorm is always cloudy, hidden behind a veil, the suffocating heat is felt, and a stripe of clouds appears on the horizon, merging into a dark solid mass.

If the fog falls down in the evening and falls on the ground, then there will be no rain tomorrow. If the fog rises up from the ground or water, it will be very hot.

Clouds are floating high - good weather.
If at sunset the sky is light azure, golden, light pink, or there is a noticeable predominance of a greenish tint, the weather is good, even if the sun is covered with clouds.
The red disk of the sun sets in a cloud or fog - to rain or wind, in darkness - to drought.
After sunset, the sky in the west turned crimson red - a sign of strong wind and rain.
If the sun rises from the reddened clouds around it - to rain, in fog - to clear, quiet and stuffy weather.
The morning sun is red - the weather will change for the worse, rain and wind are possible.
When the sun rises, it is stuffy (steamy) - it means rain on the same day.
If the moon seems larger than its normal size and is reddish in color, it means rain.
During the full moon, the moon is light and pure in color - the weather is good, dark and pale - it means rain.
At night the moon is a little reddish - the wind will bring warmth and snow tomorrow.
The stars seem very shiny - in the heat, they flicker strongly and look smaller than usual - in the rain.
A starry sky means clear weather, rare stars mean rain.
Stars in the fog mean rain, falling stars mean the wind.
If the stars twinkle strongly, and there are clouds in the morning, there will be a thunderstorm at noon.
Strong twinkling of stars at dawn means rain in the coming days.

A light rain in the morning means a good year; if bubbles form on the water from raindrops, the bad weather will be prolonged.
Dull thunder means quiet rain, and rolling thunder means heavy rain.
Prolonged rumbles of thunder mean prolonged bad weather.
If lightning flashes without thunder after rain, the weather must be clear.
If a rainbow appears in the morning before noon, it will rain; in the evening - for good weather.
If a rainbow disappears soon after rain, it means clear weather; if it stays for a long time, it means bad weather.
If rainbows appear during rain, it means rain for several days.
If at sunset and sunrise the dawn is yellow, golden, or pink, then the next day the weather will be good. A greenish color indicates that clear weather will remain for a long time.
If the dawn was red both in the morning and in the evening, the weather will be inclement. If there has been bad weather all day, and in the evening a stripe of blue sky appears in the west and the sun goes below the horizon in a clear sky, then tomorrow the weather will be clear.

Sometimes people say: “Salt gets wet - means rain”, “Soars - means thunderstorm”,

“Tobacco becomes damp - for damp weather.” What is it about? Some substances that absorb moisture from the surrounding air become damp; this happens just before rain, when air humidity increases.

There is an old folk sign: “A splinter cracks and throws sparks - a sign of bad weather.” Its explanation is similar: with high humidity, wooden objects (splinter) become damp. When burning, moisture from wood evaporates rapidly. Increasing in volume, the steam breaks the wood fibers with a crash.

Plants

The centuries-old folk experience of making long-term forecasts is based on careful observations of the world around us. And plants in this world are capable of foreshadowing an unusually wide range of various fluctuations in nature and in the weather. Some of the forecasts received the status of “folk signs”. For example, it is known that the generous and abundant secretion of birch sap in the spring foreshadows a rainy summer. And if the birch leaves bloom earlier than the alder, the summer will be warm and dry, and vice versa - the alder will be ahead of the birch - a rainy and cold summer. Summer weather can also be judged by the budding of oak and ash trees. The awakening of oak buds earlier than ash also portends a cold, wet summer.

Rowan indicates the long onset of autumn with its late flowering. It has also been noted that the abundance of fruits on rowan trees and an incredibly large harvest of berry baskets indicates a rainy autumn, while too few fruits on rowan trees indicate a dry autumn. The cherry tree determines when the real snow will fall: until the last autumn leaf falls from the cherry branches, there will be no snow, no matter how much it falls, as long as the leaves hang on the cherries, there will be a thaw. The approach of a harsh winter was judged in the fall by the harvest of acorns: there were many fruits for the cold frosty winter. No matter how heat-loving trees bloom in the spring, frosts will continue until the buds on the bird cherry and pear finally bloom.

Trees and shrubs, herbs and flowers serve us as guides in the world around us, as navigators in the weather. In addition to weather predictions, they can act as a kind of compass. Every schoolchild knows that in an open area any tree on the south side has the most leafiness and branching, since it is from the south that it is illuminated and warmed by the sun. The tree trunk itself also serves as a good compass: upon careful examination, it is easy to detect on the northern side of the pine bark a continuous vertical dark stripe that differs from the main color of the trunk. This is due to the fact that after rains and precipitation the sun, passing from east to west, illuminates and dries primarily the bark on the southern side. The northern side of the trunk retains moisture longer, in which various microorganisms and lichens that do not like sunlight settle. The birch bark from the south is cleaner, whiter and lighter, but on the northern side the birch has cracks and growths, more dark spots. Coniferous trees on the south side also have drips of resin - oleoresin. Wild lettuce is a real compass plant: its leaves always face the zenith of the sun with their edges and practically do not provide shade. The wide side of the leaf - the surface - faces east and west - this is how the plant saves itself from overheating. The leaves of eucalyptus, cotton, and tansy are arranged according to the same principle. And strawberries and wild strawberries always begin to turn red on the south side.

Scientists and botanists know about 400 species of plants that are sensitive to upcoming weather changes and play the role of unique barometers. Some of them squeeze their buds before the rain, trying to protect the pollen from getting wet and hypothermia, while others, on the contrary, begin to exude strong aromas and nectar before the onset of a thunderstorm, attracting insects and our attention. This is where the sign was born: bees attack a white acacia - it will rain. The famous adonis - the legendary adonis opens its corolla in the late afternoon, but releases nectar only before rain with increasing air humidity. In dry, clear weather, Adonis ceases to attract insects with its smell. Before the rain, honeysuckle and currants also smell strongly, although in stable sunny weather their smell is barely perceptible. Honey plants linden and buckwheat intensively produce nectar and emit aroma at air humidity of at least 60–80%, attracting insects on humid days. And another sign of rain is strong-smelling hay. Bird cherry, jasmine, rowan, violet and cornflowers - on the contrary - smell “brighter” in dry and consistently sunny weather.

An interesting barometer are thistle flowers, which on good clear days you literally cannot take with your bare hands, but before the rain the spines on the flower head close tightly and lose their tenacious qualities and prickly properties. As moisture in the air increases, the branches of spruce and pine descend lower, and the scales on the cones close together, pressing tightly against each other.

A huge number of cases related to the behavior of animals in seismically unfavorable zones have been described, but the facts that plants are able to predict seismic vibrations are practically unknown. However, there is one of the few plants that serves as a sign of an imminent volcanic eruption. This is a royal primrose growing on the island of Java along the slopes of a volcano. Only it blooms on the eve of a volcanic eruption and serves as a signal to local residents of danger. Thanks to the flower, people manage to evacuate to a safe zone in time. This property of the mysterious flowering of the royal primrose remained unstudied for a long time, until Belarusian scientists and physicists were able to provide an explanation. The thing is that under the influence of ultrasound, captured by the plant during the eruption, the osmotic pressure inside the plant increases. There is an incredible acceleration in the movement of liquid in the capillaries - the vessels of the primrose, the height of the moisture level in the plant increases, which gives it additional strength, a powerful push serves as a stimulus for flowering. And again, thanks to observations of plants, a discovery was made in science: the ultrasonic capillary effect, which found the possibility of its practical application for the needs of mankind, for example, for saturating porous materials with molten metals, etc.

The dandelion squeezes its ball - it will rain.
The clover shrinks, and the mallow flowers wilt and curl up - for the rain.
Horse chestnut leaves secrete a large amount of sticky sap before rain.
Before the rain, the flowers of a white water lily close.
Drupe bushes, hiding in the shade of trees, straighten their usually rounded leaves 15-20 hours before the rain.
In a storm, the pine tree rings, if you listen carefully, and the oak tree groans.
On the eve of a sunny day, bindweed always opens it even in cloudy weather,
Honeysuckle flowers generally lose their aroma before drought.
Before the onset of rainy weather, the flower corollas of celandine noticeably droop.
There is also this kind of grass with small oval leaves that is always wet to the touch, even in dry weather. This property of the plant is reflected in its name - chickweed, although its scientific name is chickweed. The thin white petals of its flowers, divided in two, have the appearance of an elegant star. You can predict the weather by its flowers. If the corolla of the flower does not rise before 9.00 am, it will rain during the day. This barometer can be used all summer, because... woodlice blooms from April to late autumn.
Before the onset of inclement weather, potato stalks bend and the flowers droop.
Friendly leaf fall - for a harsh winter.
There are plenty of nuts, but few mushrooms - the winter will be snowy and harsh.

Based on onions grown in the garden, you can predict the winter weather right at home: if the outer two or three dry layers of the onion skin are thin and easily torn, the weather will be relatively warm, and if the skin is rough and durable, a harsh winter should be expected.

We receive reliable information about what weather awaits us in the next day, and even hours, from domestic animals, birds, and insects.
Swallows and swifts fly low above the ground, their breasts almost touching the surface of the water - which means it is raining, although there is not a cloud in the sky yet. The explanation here is simple - the humidity has increased, the wings of the midges have become heavier, which is why it accumulates below, and the birds follow it.

Before the rain, ants rush to close the entrances to anthills. Taking care of preserving the delicate pollen, plants fold the petals of their flowers.

Fireflies do not glow at all or suddenly go out - it’s raining
Dragonflies fly in flocks - it will rain in 1-2 hours
Midges climb into your face - because of the rain.
Green grasshoppers fall silent before the rain.
The hot summer is indicated by the abundance of May beetles that appear in the spring.
The appearance of earthworms on the surface of the earth means rain.
Sparrows bathe in dust - for rain
Seagulls on the shore raise a hubbub - bad weather
When the birds are silent, expect thunder.

Homemade weather forecasters

A spruce branch is a barometer. Using the ability of coniferous trees to lower their branches before rain and raise them before clear weather, residents of the Siberian taiga have long been able to quite accurately determine the upcoming weather based on the state of the spruce crown. The ability to respond to weather changes is also preserved in dry spruce branches, which makes it possible to make simple, long-lasting barometers from them. To do this, take a 25-30 cm section of a young spruce trunk along with a 30-35 cm long branch, clear it of bark and attach the sawn part of the trunk to some vertical support (preferably to the wall of a building). The branch should be in such a state that when its free end is lowered down before bad weather and raised up in stable, clear weather, it moves parallel to the screen wall without touching it. Near the end of the “arrow” branch, a plywood, metal or plastic scale with divisions of 1 cm is attached to the wall. After some time, when the device shows its capabilities, the scale can be marked with indicators: “clear”, “variable”, “rain” , as on a conventional aneroid barometer. Long-term observations have shown that with a branch length of 32 cm, the amplitude of its deviations can reach 11 cm. This simple device predicts significant weather changes in 8-12 hours, sometimes for a longer period.

Hygrometer made from seeds with awn. The seeds of some plants have awns that quickly and sensitively respond to changes in air humidity: at high humidity they straighten (unwind), and in dry air they curl into a spiral. Therefore, a simple but sensitive hygrometer can be made from them. For this purpose, the most suitable fruit is the one with the spine of such a ubiquitous annual low weed plant as hemlock (Fig. 13). If you pierce a hole in the center of a circle of cardboard with a diameter of 5-6 cm and fix the lower end of the fruit (seed) in it with a drop of glue, then in dry weather its crescent-shaped tip will deviate along the circumference counterclockwise (to the left), and when humidity increases – back (to the right).

Slide-hygrometer. A fairly accurate weather predictor can be made from a transparency. To do this, you need to photograph some summer landscape. It is advisable that the negative depict vegetation with a river or lake. A positive print should be made on a photographic plate. After developing, fixing and washing, the slide is immersed in a 10% solution of cobalt nitrate for 15 minutes and dried without washing. Using a dry emulsion, the trees, shrubs and grass depicted on it are painted over with yellow watercolor paint, such as gummigut. They edge the transparencies and hang them between the window frames. As fine, dry weather approaches, the sky and water in the transparent photograph will turn blue, and the vegetation will turn green. But as soon as the weather begins to worsen, nature will fade: the sky and water will turn gray, and the leaves and stems will turn yellow.

Barometer from immortelle. You can also use a bouquet of flowers to predict the weather. If well-dried immortelle flowers on stems are treated with a solution of 200 g of water, 4 g of glycerin and 30 g of cobalt chloride, a bouquet of dried flowers before bad weather will acquire a yellow color, and with the onset of clear sunny weather, the flowers become bright green.

Often in the old days, to predict the weather, a mature fir cone or a bunch of chicken feathers was tied on a cord: in bad weather, the scales of the cone would close and the feathers would droop.