Screw

Have you ever twisted the lid of a jar or screwed in a light bulb in the socket? If so, then you’ve used a screw!

A screw is one of the most useful simple machines. It helps hold things together and move objects with less effort.

At its core, a screw is just an inclined plane—a slanted surface—wrapped around a cylinder. The raised spiral on it is called the thread.

When you turn a screw, the spiral thread converts your rotational motion into linear motion, which is movement in a straight line.

Each twist pulls the screw deeper into the material, holding things tightly in place.

Screws do more than fasten wood or metal. Think about jar lids. Their threads make tight, secure connections.

Screws give a mechanical advantage, meaning they multiply the force you apply. When you turn a screw, your small rotational force becomes a stronger forward push.

This is why the screw’s output force is greater than your input force, and why its mechanical advantage is always greater than 1.