Unit 11:  Heat and temperature                                    1   2   3   4   5   6

3. Heat and thermal equilibrium

When two bodies come into contact, the particles with more kinetic energy transfer some of their energy to the other particles with less energy.

This energy transfer occurs because the particles collide with each other: finally, all the particles have the same amount of kinetic energy.

In this process:

- The body that had a lower temperature has gained thermal energy and so its temperature has increased.

- The body that had a higher temperature has lost thermal energy and so its temperature has decreased.

Both bodies finally have the same amount of thermal energy, so they also have identical temperatures. This state is called thermal equilibrium.

Heat is the transfer of thermal energy between two bodies when they are at different temperatures.

Heat is always transferred from the body with the highest temperature to the body with the lowest temperature, independently of their respective sizes. The transfer of energy stops when both bodies

Reach the same temperature.

Animation: Thermal equilibrium (Tutorvista)

3.1. Answer the questions:

        a. Is heat a type of energy?

        b. Is the same temperature than heat?

        c. Which is the unique condition to transfer of heat occurs between two

            bodies?

3.2. If you hold a copper rod supporting one of its ends on a block of ice, you will observe that the rod will cool down quickly.

        Does it mean that cold has been transferred from the ice to the rod? Explain your answer.