Force
Forces and Motion

Identifying lengths and distances on the lever

Teaching Guidance for 11-14 Supporting Physics Teaching

Length and distance

Thinking about the teaching

If I apply a force to the end of a lever there are two measurements, both in metres, which I might pay attention to in describing the event:

  • The length, L1, from the pivot to the line of action of the force
  • The distance, D1, that the force moves as the lever pivots

Teacher Tip: Keep the lengths (L1, L2) from the pivot to the line of action of the forces separate from the distances moved by those forces as the lever spins (D1, D2).

This will help you think about either moments or energy.

To analyse the action of the lever in terms of moments:

  • You'll need to consider the size of the force acting and the length from the line of action of the force to the pivot (L1).

To analyse the action of the lever in terms of energy:

  • You'll need to consider the size of the force acting and the distance moved by that force (D1).
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