A science teacher told me that heat does not rise. He said that cold air falls and displaces the hot air.True?

Answer 1

If that were true, then a hot-air balloon wouldn't work. The hot air has to have an active rising motion in order for the balloon to rise and stay aloft. There is simply not enough force in the cold air underneath it to lift it up by itself. Hot air is less dense than cold air, so it creates bouyancy in a cold-air environment.

He's full of hot air.

Answer 2

The point your science teacher is trying to convey is that heat does not do anything with respect to gravity. If I heat a metal pipe in a vacum and wait for the other end to get hot, it won't matter what orientation the pipe is placed (unless, of course, you melt the pipe). The same amount of time will occur before the other end reaches some specific tempurature.

If your science teacher is implying that its the cold air doing the action... I'd disagree. But it also might be likely you've misinterpreted him. Its actually the whole system trying to reach equilibrium. Cold air does displace the hot air. The hot air also is expanding and displacing the cold air. You cannot write this as some object X is the only thing performing some action something to object Y. Both X and Y are involved in the action.

Answer 3

I'm thinking your science teacher is wrong. In meteorology for instance there a point in the air column where air lifted mechanically (forced up a mountain side) meets a point called the level of free convection. After that point the air continues to move upward even if the lifting force is no longer present. The LFC occurs when the air being lifted is warmer than the surrounding air mass. Also in the case of cold air laying in bottom of a valley in still air forms fog. When the morning sun warms the air close to the ground it rises and the cold air then moves in to replace it. Not the other way around

Answer 4

I think your teacher's point must be that while it is not correct to say that "heat rises," it is true that warm air rises. Any mass of air or any other gas that is relatively warmer than the surrounding air or other gas will rise.

When the warm mass of air rises, it leaves a relative low pressure area below it, which will tend to be filled by cooler air from the surrounding mass, which in turn results in cooler air from the surroundings descending to take the place of the cooler air that moved in to take the place of the warm air that rose.

So it's hot air, not heat that rises. That is why a hot air baloon rises. Pure heat is radiant energy and tends to be radiated in all directions.

Answer 5

Does Heat Rise

Answer 6

Okay, when air is heated, the air particles start vibrating vigourously and the attraction between each air particles will not be as strong, The particles will spread far apart as compared to cold air. So, there will be less air particles in hot air in a specific volume, and there will be more air particles in cold air in that specific volume. Due to this difference, hot air will rise above cold air...

Answer 7

Let's not malign the teacher. His point of view can be justified. But the real truth, which I did not read in any of the responses, is that "hot air is less dense than cold air". Buoyancy is the key factor. Hot air balloons rise because the heated air in the balloon is less dense than the cooler air around it.

Answer 8

As warm air rises the cold air moves in beneath it to fill the space where the warm is rising from. In order for anything to move it has to have energy, and in the case of the hot air that energy is heat. There is no "cold" form of energy...so it's not the cold air that initiates the movement.

Answer 9

False! Your teacher is an idiot! (no offense)You can prove that heat rises yourself. If heat doesn't rise, then how does a fireplace not fill the house with smoke? If heat doesn't rise then why is the air hotter the higher you go in a house? If heat doesn't rise then what is that
"wind" you feel off of the top of a kerosene heater?
You can disprove him many ways but he cannot prove you wrong!
You could also ask him "Then how do hot air balloons work?"
or "How does weather work?"

Answer 10

Tell your science teacher that he is an idiot....He need to go back to collage, if he even went to one. If his "theory" were true...how does he explain fog or even clouds. Fog and clouds are cooler air with very high moisture content. They hover over warmer air or are suspended in it. A very simply example of this wound be a lighter or matches. When you light them, which direction does the flame and hot air go ???? It goes up.... And it is not displacing anything because it is self contained and ignited.Yes it is using oxygen (cooler air) to burn, but it is not displacing it.