A screw is a simple machine that converts rotational motion into linear motion, allowing it to do work effectively in various applications, such as holding objects together or lifting materials.
When you turn a screw, its spiral thread engages with the material it is driving into, which creates both friction and resistance. This action causes the screw to move in a linear direction—either deeper into a surface or allowing it to draw two materials together. The force applied while turning the screw is concentrated along the threads, which allows it to generate substantial holding power with relatively little effort.
The mechanical advantage of a screw comes from the angle of its threads; the steeper the angle, the more force is required to turn the screw but the greater the lifting power it provides. This is why screws are commonly used in construction and mechanical applications to secure components tightly or lift objects vertically.