In a closed isolated system, a small rigid ball is held at height h1, which we will call state A. By remote control a pin is pulled and the ball is released. It falls to height h2, called state B. Calculate the change of entropy S of the system. Is it a reversible or irreversible process?
Delta S = Delta Q/T
The Attempt at a Solution
My attempt is that since the system is isolated that means no heat is transferred and the entropy is not changed at all.
But again, since the position of the ball is now lowered, it also means it has lost some potential energy, so change in Q can be related to change in energy which can be mg(h1-h2), with T being constant. So am not sure which one is the right answer.
Also sometimes I think it is an irreversible process because external work will be needed to bring the ball back to its original height but then I also get confused that it might be reversible process because it's an closed isolated system.
Thanks for your help in advance!