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AS Daily A Level Physics question

2026-02-24 OCR A Dynamics: terminal velocity and drag (qualitative) OCR-A Module 3.2 Forces in action — drag and terminal velocity (qualitative) OCR-A Module 3.2 Newton’s laws — equilibrium of forces at terminal speed

A skydiver of fixed mass descends steadily at terminal speed with parachute A. They then use parachute B of the same design but with double the canopy area, in the same air conditions. At these speeds, the drag force is proportional to (canopy area) × (speed)². What happens to the terminal speed with parachute B compared to parachute A?

  1. A It halves (0.50× the original).
  2. B It stays the same (1.00× the original).
  3. C It decreases by a factor of √2 (≈0.71× the original). (correct)
  4. D It increases by a factor of √2 (≈1.41× the original).

Answer

The correct answer is C.

Correct: C — It decreases by a factor of √2 (≈0.71× the original). At terminal speed, weight equals drag, so mg = k A v²; with the same mass, v ∝ 1/√A, hence doubling A makes v become v/√2. A halves (0.50×) assumes v ∝ 1/A, ignoring the square on speed. B suggests area does not affect terminal speed, which contradicts drag depending on area. C is correct because doubling area requires a lower speed so that k A v² still balances mg, giving the √2 factor. D reverses the relationship, implying larger area would increase terminal speed.

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