Simple Machines

Screw

Picture
A screw is a post with threads wrapped around it.  If you were to unwrap those threads they would actually form an inclined plane.  Imagine the screw on the top of a water bottle.  Even though it takes you longer to screw on the top you need less force to secure your water bottle in place.  We use screws all the time to secure things in place.  Look at how your desk or chair is assembled.