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Lesson · Grade 5 · Science

Levers: Fulcrum, Effort and Load

  • Grade 5
  • Science
  • 1 min 1 s
  • British Columbia
  • BC5-SC-09

A bar resting on a fulcrum with a rock on one end is labelled step by step: lever, fulcrum, load and effort. Pushing down lifts the rock. When the fulcrum slides toward the rock, the effort arm gets longer and a smaller push lifts the same rock, though the pushed end has to move farther.

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In one sentence

The question this lesson answers

How can a small push lift a heavy rock?

A lever is a stiff bar that turns on one point.

Transcript

What the lesson says

How can a small push lift a heavy rock?

A lever is a stiff bar that turns on one point.

The point it turns on is called the fulcrum.

The load is the thing we want to lift, like this rock.

The effort is the push or pull we put on the lever.

Push down on this end, and the rock on the other end goes up.

The load arm is the distance from the fulcrum to the load.

The effort arm is the distance from the fulcrum to the effort.

Right now, the two arms are the same length.

Now slide the fulcrum closer to the load.

Now the effort arm is much longer than the load arm.

So a smaller push lifts the same rock.

But your end of the lever has to move farther.

The longer the effort arm, the less effort you need.

Curriculum

Where this fits

British Columbia, Grade 5

Science, Physics: properties of simple machines and their force effectsBC5-SC-09

Previous: Six Simple Machines and What They DoNext: Pulleys: Changing the Direction of a Pull

The outcomes and strands follow the British Columbia curriculum.

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