Forces and Motion

Keep it on the level!

Classroom Activity for 11-14 Supporting Physics Teaching

What the Activity is for

Experiencing turning effects.

Here the pupils can get a direct feel for the turning effect of a force acting on a lever because they have to oppose that turning effect.

What to Prepare

  • a retort stand rod or length of stiff strong dowel, approximately 60 centimetre long
  • an object that can be suspended from the rod (about 500 gram is suitable)

What Happens During this Activity

Work in pairs. Pupils hold the rod horizontal (or try to) as the object is gradually slid out towards the end of the rod. Pupils should be encouraged to describe what they feel, firstly in terms of what they had to do to keep the rod horizontal, and then in terms of the effect of the force provided by the mass.

Pat: The force stays the same, but I have to try much harder to keep the rod horizontal. This is because the same force has a larger turning effect. The force has a larger turning effect because it is farther from the pivot.

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