Question

why can we not move a wall by applying force

Answer 1

Answer:

When we exert force on the wall, to understand the entire phenomenon we have to analyze it from the molecular phenomenon. The muscle fibers in our hand are being used to exert force on the atoms of the wall, but since they attraction is greater than the force exerted, only some of the atoms of the wall are displaced and no macro effect is seen. But since our muscles applied force but no displacement was observed, technically speaking the work done is zero, but still we feel exhausted. So, this is the reason we can't move a wall by applying force.

hope it helps.