How can a small push lift a heavy box?

A seesaw is a simple machine called a lever. It is a long stick that can tip on a stand. The stand has a name too: the fulcrum.

Put a heavy box on one end and push down on the other end. If the stand is in the middle, you need a push as heavy as the box.

Now slide the stand closer to the box. The long side that you push is now much longer than the short side that lifts. A small push can lift the heavy box!

But there is a catch. Your end has to move a long way down so that the box moves up a little. You push gently but far, and the box lifts strongly but only a bit.

People have used levers for thousands of years. Scissors, bottle openers and wheelbarrows are all levers in disguise.