Question

1. When a person pushes hard on a solid wall, is work done?
2. Why is it tiring to push hard against a solid wall?

Answer 1

1.

Because for work to be done, 3 conditions must be met:
1. There must be a force acting on the object.
2. The object has to move a certain distance called the displacement.
3. There must be a component of the forces in the direction of the motion.

in the case of pushing the wall, there is no distance covered or what we call displacement. That condition alone is missing therefore there is no work done.

2. it's one of newton's law which is for every action produces an equal reaction. since you are pushing the wall with great energy, the wall is pushing you with the same energy. Because of the balance in energy, neither the wall or the person pushing is moving but energy is still spent.