Question

The temperature of a body is an indicator of:
A. The total energy of the molecules of an object
B. The average energy of the molecules of an object
C. The total velocity of the molecules of an object
D. The average kinetic energy of the molecules of an object

Answer 1

Hint: When thermal energy is given to a body, its molecules start vibrating or moving at higher velocities. This leads to an increase in the average kinetic energy of the molecules as a whole. This leads to an increase in the temperature of the body and it feels hot.

Complete step-by-step answer:
There is a direct correlation between the temperature of a body and the average kinetic molecules of the body. When energy in any form (most commonly thermal), is provided to a body, the molecules gain this energy and start to vibrate more vigorously or even start to move far apart with greater velocity. This in turn leads to an increase in the average kinetic energy of the molecules as a whole since kinetic energy of a body depends directly on the square of its velocity.
This leads to an increase in the temperature of the body and the body becomes hotter.
Hence, it can be said that more the temperature of the body, more will be its average kinetic energy.
Hence, the temperature of a body is an indicator of the average kinetic energy of the molecules in it.
Therefore, the correct option is D) The average kinetic energy of the molecules of the object.

Note: A student might get confused and think that the temperature might be an indicator of the average energy of the molecules of the object. However, this is not true. It depends only on the average kinetic energy of the molecules.
One way to get a feel for this is to think that when we lift a box from the ground floor to the second floor of a building, the gravitational potential energy of all the molecules in the box is increasing and hence, the total average energy of the molecules increases, but this does not lead to an increase in the temperature of the box. Hence, temperature does not depend on the average energy of the molecules but only on the average kinetic energy of the molecules.