How can screwing a massively heavy object to a wall with four screws (like a water tank) be safe? I feel its always going to fall, taking a piece of the wall with it.

Question

Or screwing workout equipment which you constantly pull with your own weight.

EDIT: Forgot to add, I’m not in the US, I’m talking about brick or concrete walls, not drywalls. Although probably the basic principle applies when it comes to explaining how force works.

In: Physics

Answer 1

A lot of people have added stuff but another major factor is most force is going to be towards the ground and so perpendicular to the fastener. Things that are designed to be attached to the wall generally have the most weight placed as close to the wall as possible so there is the least amount of pulling away from the wall.