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

Think of it like a big cup of water. When you try and push the cup over, the water in the bottom doesn’t want to let it fall over, and it’ll just tip back upright. But if you push it JUST far enough, the weight of the water makes it tip all the way and spill all over. Screwing the top of the cup to a wall prevents it from ever getting to that tipping point, even if it doesn’t have any water in it.