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AS Daily A Level Physics question

2025-10-27 OCR A High level GCSE physics — Kinematics (M3) 3.1.1(a)

A runner completes the same 1.2 km lap on two days. On day 2 their average speed is 50% greater than on day 1. Compared with day 1, what happens to the time to complete the lap on day 2?

  1. A increases by 50%
  2. B decreases to two-thirds of the original time (about 33% shorter) (correct)
  3. C no change, because the distance is the same
  4. D decreases by 50% (half the time)

Answer

The correct answer is B.

Correct: B — decreases to two-thirds of the original time (about 33% shorter). Time for a fixed distance is inversely proportional to speed, so increasing speed by 50% makes time t2 = t1/1.5 = (2/3)t1. A is wrong because it treats time as directly proportional to speed, which reverses the actual relationship. B is correct for an inverse change: 1.5 times faster gives two-thirds the time. C is wrong because time depends on both distance and speed; same distance does not fix the time. D is wrong because halving the time would require doubling the speed, not a 50% increase.

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