Wally now lift the box of the floor and put it on a shelf. Does he doing any work? If not why? If so .what energy change is accurring?

The change of potential energy is

ΔPE =mgΔh
Work W = ΔPE

To determine if Wally is doing any work, we need to consider the definition of work in physics. In physics, work is defined as the amount of energy transferred by a force when it causes an object to move.

If Wally lifts the box from the floor and places it on a shelf, he is indeed doing work. This is because he is exerting a force on the box, causing it to move against the force of gravity. The energy is being transferred from Wally's muscles to the box.

The energy change occurring in this scenario is a conversion of potential energy. As Wally lifts the box against the force of gravity, the box gains gravitational potential energy. When he places the box on the shelf, the potential energy is converted to potential energy stored in an elevated position.

In summary, Wally is doing work when he lifts the box, and the energy change involved is a conversion of gravitational potential energy.