Misconceptions about thermodynamics – Does heat really rise?

By Don Lincoln, PhD, Fermila National Emergency Laboratory (Fermilab)

There are many misconceptions and misunderstandings about thermodynamics. One of the most common is the idea of ​​heat. It is often said that people should not be questioned. Although there is a particle of truth in it, it is weakened to the extreme. Let us know what is right and what is wrong.

There are three ways in which heat is transmitted: the study of transmission, radiation, and convection. (Photo by Darryl Brooks / Shutterstock)

What is heat?

At least everyone knows what heat means. It warms you. You feel the heat coming from the fire. On a cold day, you feel warm when you put your hands on a steaming coffee. However, there is a simpler and more experienced idea of ​​what the temperature is and what is more technically accurate.

In physics, heat is a kind of energy. Even more technically, heat is a type of energy that can be transferred from something hot to something cold.

By trying to combine technical and language, something fresh can transmit heat. If you take water directly from the tap, the chances are great. Suppose you take two identical jars and fill them with the same amount of water. Then set one pot aside and place the other on your stove to heat it.

A white bath with hot water flowing from the tap, and a woman's left hand are held under the water to check how hot it is.
It does not matter if you put your hand in hot water, if you put your hand up or down, your hand will still be warm, indicating that the heat exchanger will not participate in the heating. (Image Africa Studio / Shutterstock)

How are those two pots different now? Well, one is obviously cold and one is hot. So, how did that happen? Well, use the stove to heat energy in a pot. That energy is now stored in water.

Where does that power really go? Water is H20, which means that you can assume that the water pot contains small water molecules, such as small tumors.

As you add energy to the water, the marbles begin to move faster. They zoom in quickly, and they spin. In these water molecules, they can also vibrate. Water molecules look like small Vs, and the molecules can flex and vibrate and do all sorts of things.

At the atomic level, this is exactly what happens when you boil a pot of water.

When people say it’s hot, they mean one place is hot and one place is cold. Literally, the phrase “heat rises” probably means that the surface above the object is heated, the object itself cools. So we are talking about how heat is transmitted.

Learn more about the world’s misconceptions about science.

Behavior

There are three ways to transfer heat. There is a transmission that involves direct contact with the hot object. One example is dipping your hand in warm water. The vibrations of the hot water molecules shake the molecules of your hand, thereby accelerating them. And if molecules move, bend, and vibrate, that is thermal energy. This means that your hands are warm.

Now, you can put your hand on top of the water, under the water or anywhere in the water, and your hand will warm up. And in a pot, the bottom water can be heated well. This clearly indicates that the heat exchanger does not participate in the increase in temperature.

In interaction, the molecules vibrate faster than the slow ones, and only the slower ones accelerate. The only thing that matters here is the interface between vibrating and non-vibrating molecules.

This is a copy of the video series Understanding the misconception of science. Watch now on Wondrium.

Radiation

The second way heat is transmitted is called radiation. This happens when something is heated enough to emit electromagnetic radiation. If you put on fire, you will see the light shining. That is visible light. But you cannot see all kinds of electromagnetic radiation. Some species are invisible.

It is called an infrared ray. Infrared radiation causes things to start moving – rotating, shaking, and so on – which means they heat things up. In a campfire, you should not be overheated to feel the heat coming to you. You can sit next to it and warm your hands or feet. Obviously, that thermal energy does not move sideways. Therefore, heat transfer due to radiation does not follow the rules of heat transfer.

Learn more about radiation.

Transfer

However, if you put your hand over the fire and not just to the side, the result is very hot. If you do, it is very easy to burn yourself. If the temperature above the fire heats up next to the fire, does that mean it will rise? Well, sort of. There is a third type of heat loss that follows the rules of warming, and that is called convection.

Convection occurs when the heat source is in a moving medium, such as air or water.

For example, if you place air near a hot object, the molecules that move the hot object transmit heat energy into the air. But if that moth starts to absorb heat and the molecules start to move, they take up a little more space. This is because the molecules move and jump into other molecules, pushing them. The result is vibration in the middle – in this example, air – and the result is that the air is less dense.

If it is moderately dense, such as air or water, it will rise in the middle. This is basically how air-filled objects, such as pool toys, float. They are less dense.

Iron stove with a burning fire in it.
In parallel, it can be said that in the case of transport, heat is generated, but in reality the first real heat transfer occurs due to management. (Image: Shutterstock)

So, what happens to a room in a wood-burning stove is that the air near the floor of the wood-burning stove absorbs heat through the propeller. Then the air gets stronger and goes up into the rest of the air and leads to the roof. The very cold roof encounters hot air and some air molecules cause the roof molecules to move, and the roof heats up.

So, although it is said to be related to each other, in a distorted state, heat rises, the real effect is air heating.

Temperature fluctuations cause the air molecules to move faster, which in turn causes them to lose weight. Cool and dense air descends, which in turn causes hotter and less dense air to rise, and the heat is removed. But the first real heat transfer is due to the transfer.

Convection is a secondary process that, in fact, carries heat from one place to another in a room.

Common questions about heat and heat transfer

Q: Does the heat really rise?

Heat is a type of energy, and there are three ways in which energy is transmitted: Transmission, radiation and transmission. A simple study shows what happens when infrared radiation is directed at heat and heat Heat does not rise. When a convention is created, one can say that there is heat, but in reality, the first real heat transfer occurs because of work. This is because convention is a secondary process.

Q: How does transmission work?

In Leadership, The vibrating molecules slowly interact with the vibrator, and the slow ones run faster. That’s it Heat is transmitted. So, if you put your hand in hot water, the vibration of the hot water molecules will shake the molecules of your hand, thereby speeding up and warming your hand.

Q: Where does infrared radiation come from?

Infrared radiation It is a type of electromagnetic radiation caused by heating a vessel. Infrared radiation causes things to start moving – rotating, shaking, and so on – which means they heat things up.

Q: What brings about a convention?

Transfer Occurs when you take a heat source and put it in a portable medium, such as air or water. So, for example, when air begins to attract heat and the molecules begin to move, they take up a little more space. As a result, the air becomes less dense. However, since convection is a secondary process, the first real heat transfer is done by working.

Keep reading
Some facts, and many misconceptions of modern science
The birth of modern science
Changes in scientific methods and subsequent theories

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