Where should I push a lever to lift something easily?

Think of a seesaw at the playground. You sit down on one end, and with a little creak, your friend on the other end floats up into the air. You can feel the board tip under you as it moves.

Now picture a grown-up sitting on the other end instead. A grown-up is much heavier than you, and lifting them feels hard. A seesaw is a kind of lever, a long, stiff board that tips. So where should you push a lever to lift something heavy easily?

Every lever rests on one spot and tips around it. That spot is the fulcrum, which means the point a lever rests on and turns around. On a seesaw, the fulcrum is the bar under the middle of the board. It holds the board up, so one end can go down while the other end goes up.

Let's say your grown-up sits on the seesaw close to the fulcrum. You stand on the other side and press down on the board with your hands. When your side goes down, the board turns, and their side has to rise. Do you think pressing is easiest right beside the fulcrum, or far out at the end?

Far out at the end is the easy spot! When you press right beside the fulcrum, the board hardly moves, no matter how hard you try. When you press at the far end, your grown-up starts to rise.

Out at the far end, your hands swing down a long way. Your grown-up, sitting close to the fulcrum, rises only a little way. A lever lets you trade a long, gentle push for a short, strong lift.

Now let's have your grown-up slide out to the far end of their side. Their end has to swing a long way too, and your push can no longer lift them. So the heavy thing belongs close to the fulcrum, and your push belongs far away from it.

A gardener uses the same trick to move a big rock. The gardener slides one end of a long metal bar under the rock, close to a small stone that works as the fulcrum. Then the gardener pushes down on the far end of the bar, and the heavy rock tips up.

Today's key word is fulcrum. When you push far from the fulcrum and keep the heavy thing close to it, your long, gentle push becomes a short, strong lift.

The next time you sit on a seesaw, you will know where to push, so rest well and dream of gentle, easy lifts.