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AS Daily A Level Physics question

2026-01-10 OCR A Moments and equilibrium (M3.2) 3.2.3(c)

A mechanic tries to loosen a rusted nut with a spanner. She pushes down with the same force at the very end of the handle. She swaps to a spanner with twice the handle length, applying the force in the same direction at its end. What happens to the turning effect (moment) on the nut?

  1. A It halves, because the longer handle spreads the force over a greater distance.
  2. B It stays the same, because the force on the nut is unchanged.
  3. C It doubles, because the perpendicular distance from the pivot is doubled. (correct)
  4. D It increases slightly at first and then decreases, because the angle of the force changes with length.

Answer

The correct answer is C.

Correct: C — It doubles, because the perpendicular distance from the pivot is doubled. A — Wrong: the same force applied further from the pivot produces a larger turning effect; it is not ‘spread out’. B — Wrong: the turning effect depends on both the force and its perpendicular distance from the pivot, not force alone. C — Right: with constant force, doubling the perpendicular distance doubles the moment. D — Wrong: the force direction is the same in both cases, so the angle does not change; only the distance increases.

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