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

You’re screwing it into the framing behind it. That framing is either wood that is being compressed as the screws enter, holding a very tight grip on it, or it’s metal framing that has very high strength potential.