Explain how a lever can be used to lift a heavy load using a small effort force. Refer to moments in your answer.

A lever is a rigid bar that rotates about a fixed point called the pivot. The turning effect of a force is called a moment, calculated as

moment = force × perpendicular distance from the pivot.

In this case the gardener applies a small effort force at a point on the bar that is far from the pivot, while the heavy boulder is held at a point close to the pivot. Because the effort distance is greater, the effort force produces a larger moment than the same force applied close to the pivot.

For the lever to lift the boulder the clockwise moment produced by the load must be balanced by an anticlockwise moment produced by the effort. Since the effort distance is larger, a smaller effort force can generate a moment equal to or greater than the load moment, allowing the boulder to be raised.

Thus a lever can lift a heavy load with a small effort force by using a greater perpendicular distance to create a larger moment, achieving equilibrium or a net anticlockwise moment that lifts the load.