Q. Consider two identical homogeneous balls, A and B, with the same initial temperatures. One of them is at rest on a horizontal plane, while the second one hangs on a thread. The same quantities of heat have been supplied to both balls. Are the final temperatures of the balls the same or not? Justify your answer. (All kinds of heat losses are negligible.)

Answer & Explanation: 

The final temperature of the ball (A) hangs on a thread will be more than the ball (B) resting on the plane. As heat is given to the balls, both will expand.

On expansion, center of mass of ball A will fall whereas in case of ball B, it will move up. 

Hence a part of heat energy given in case B will be utilized to raise potential energy alos hence its temperature rise will be less than ball B. 

However in general situation we neglect this effect.