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

Screws, bolts, and nuts produce an incredible amount of clamping force. A screw is basically two very low incline ramps or shims being pushed against each other. It takes very little force turning the screw (torque) to create a huge force in the axis of the screw or clamping force. For example the force holding your wheels to your cars is over ten times the weight of the car PER WHEEL. Just from 5 little nuts torqued to ~100ft/lbs or someone pressing a foot long wrench with 100lbs of force.

Edit: Misread the point of the question, yes typically heavy things are not screwed into the drywall but into the frame of the house itself.