What is heat Heat transfer Heat laws Daily lives

How can the air conditioner cool down the temperature?

The air conditioner can cool down the temperature because it can take out the heat from the air in the room to the air which outside the room. There is some liquid inside a high pressure, narrow pipe and then go into a low pressure, wide pipe. When the liquid go through this two pipe, it will change states from liquid to gas. So, it need to absorb energy from the air in the room. Then the gas will go through the narrow pipe. Because of the pressure, the gas will change state into liquid again. Changing into liquid, it need to give out energy and the energy will transfer to the air which outside the room. By transferring the energy, the air conditioner can down the temperature.

How can a thermos save the temperature?

A thermos is made as the follow:

Vacuum water

Because heat is transferring by the collision of the atoms, heat can only transfer by the cup. The space inside the cup is vacuum, no atoms inside it. So heat is transferring very slow, and the thermos can save the heat energy.