How does a screw act as a simple machine?

A screw functions as a simple machine by converting rotational motion into linear motion. When you turn the screw, the rotational force you apply around its cylindrical shape translates into a direct linear movement along its threaded shaft. This ability to convert one type of motion into another is fundamental to the operation of many simple machines, as it allows the screw to drive itself into materials, pull objects together, or maintain tension.

In practical terms, this means that when you rotate a screw, the threads grip into the material, pulling it along the axis of the screw's rotation. This is why screws are utilized not only as fasteners but also in devices like vises and jacks, where they lift or hold objects in place by converting the energy from your hand's rotational motion into a useful linear force.