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AS Daily A Level Physics question

2025-10-23 OCR A Foundations of Physics (M2) 3.1.3(a)

A lab bench is 1.25 m high. A student launches two identical steel balls horizontally from the same edge: Ball 1 at 2.0 m/s and Ball 2 at 4.0 m/s. Air resistance is negligible. Which statement must be true?

  1. A Ball 2 reaches the floor in half the time of Ball 1 because its speed is doubled.
  2. B Both reach the floor at the same time, about 1.0 s after launch; they land the same horizontal distance from the bench.
  3. C Both take longer than 1.0 s to hit the floor because the path is diagonal; Ball 2 lands farther away but also later.
  4. D Both hit the floor at the same time, about 0.50 s after launch; Ball 2 lands roughly twice as far from the bench as Ball 1. (correct)

Answer

The correct answer is D.

Correct: D — Both hit the floor at the same time, about 0.50 s after launch; Ball 2 lands roughly twice as far from the bench as Ball 1. The time to fall depends only on the vertical drop: 1.25 m ≈ (1/2) g t^2 gives t ≈ sqrt(2×1.25/9.81) ≈ 0.50 s, independent of horizontal speed; horizontal range is speed × time, so doubling speed doubles range. A The horizontal speed does not affect the time to fall; doubling it does not halve the fall time. B The time is about 0.50 s, not 1.0 s, and equal gravitational pull does not make the horizontal distances equal because horizontal distance scales with horizontal speed. C The path being diagonal does not increase the time; the 1.25 m drop sets t ≈ 0.50 s, and while Ball 2 lands farther away, it does not land later. D States the correct independence of motions, the correct approximate time, and the correct 2:1 range ratio.

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