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AS Daily A Level Physics question

2025-10-09 OCR A Mechanics & Materials (M3) 3.1.3(a) 3.1.3(b)

Two identical balls are released from a balcony 5.0 m above level ground at the same instant. Ball P is dropped from rest. Ball Q is projected horizontally at 8.0 m/s. Air resistance is negligible. Which statement must be true when they strike the ground?

  1. A They reach the ground together; their vertical velocity components are equal and downward, but Q’s overall speed is about 1.3 times P’s. (correct)
  2. B Q reaches the ground later because horizontal motion lengthens the fall; both have the same overall speed on impact.
  3. C They reach the ground together; Q’s vertical velocity component is larger in magnitude because its total impact speed is larger.
  4. D Q reaches the ground earlier due to its extra horizontal speed; P’s final speed is larger since it falls straight down.

Answer

The correct answer is A.

Correct: A — They reach the ground together; their vertical velocity components are equal and downward, but Q’s overall speed is about 1.3 times P’s. A Both have identical vertical motion (same height, initial vertical speed zero), so equal landing times and equal downward vertical components; P’s impact speed ≈ sqrt(2gh) ≈ 9.9 m/s, Q’s ≈ sqrt(9.9^2 + 8.0^2) ≈ 12.7 m/s, so about 1.3× larger. B Horizontal motion does not affect the time to fall, and the overall speeds are not equal because Q has an additional horizontal component. C The vertical component is set by the fall alone, so it is not larger for Q; having a greater total speed does not increase the vertical component. D Extra horizontal speed does not make Q land sooner, and P’s final speed cannot exceed Q’s because Q has the same vertical component plus a horizontal component.

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