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Physics (AS & A Level) · Feb / March 2025 · Paper 12 · Question 9

9702Turning effects of forces

The diagram shows a child X of mass 20 kg and a child Y of mass 15 kg seated on a uniform plank. The plank has a mass of 7.0 kg and has a pivot at its midpoint. The plank is horizontal and in equilibrium. Which statement about the weight of the plank is correct?

  1. AThe weight of the plank can be considered to be acting at its midpoint.
  2. BThe weight of the plank is causing an anticlockwise moment.
  3. CThe weight of the plank is causing a clockwise moment.
  4. DThe weight of the plank equals the force on the plank from the pivot.

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Correct answer: A. The weight of the plank can be considered to be acting at its midpoint.

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