In which of the following cases is mechanical work not performed? 1. The boy climbs up the stairs

In which of the following cases is mechanical work not performed? 1. The boy climbs up the stairs. 2. Water presses on the bottom of the tank. 3. The apple falls from the tree to the ground.

For a correct, clear and understandable answer to this question, it is first of all important to understand what mechanical work is.

Mechanical work is scalar work. And if you describe it, it turns out that this is when one body presses on another.

Well, now we can choose.

In case 1, when the boy climbs the stairs, this is not mechanical work.

At 3, when an apple falls, it is also not a job.

But at 2, when the water presses, the action is performed. This would be the mechanical work that needed to be found.