Question

A ball is dropped onto a smooth floor. It deforms elastically, and then returns to its original shape as it rebounds to its original height. Air friction is negligible. Which of the following statements best describes the thermodynamic change in the ball?

a. The entropy of the ball increases b. The entropy of the ball is unchanged c. The temperature of the ball decreases d. The enthalpy of the ball decreases

Answer 1

The answer is entropy of the ball is unchanged.

Since it is elastic deformation so the energy gained due to compression while hitting the ground is equal to the energy released when the ball restore its original shape. Overall, we can see that energy released = energy gained so there is no release or absorption of energy per unit time during the whole process. Hence, Entropy of the ball does not change.

While we know that during a process work done is practically zero moreover air friction almost nil. So, there is no change in temperature. and for this reason the entropy also doesnot change.

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