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AS Daily A Level Physics question

2025-10-31 OCR A Kinematics — linear motion with g=9.81 (M3) 3.1.2(a)(i)

In a lab drop test, two identical steel balls are released from a balcony 20 m above the ground. Ball 1 is dropped from rest; Ball 2 is given a small downward push so it starts at 2.0 m s^-1 downward. Air resistance is negligible. Which statement must be true during their fall?

  1. A Both balls have the same downward acceleration, g = 9.81 m s^-2, throughout the fall. (correct)
  2. B The pushed ball has a greater downward acceleration because its downward speed is larger.
  3. C The dropped ball has a greater downward acceleration because it is in free fall from rest.
  4. D The pushed ball’s downward acceleration decreases as it falls so that total energy stays the same.

Answer

The correct answer is A.

Correct: A — Both balls have the same downward acceleration, g = 9.81 m s^-2, throughout the fall. B is wrong because acceleration due to gravity near Earth does not depend on how fast the object is moving. C is wrong because starting from rest does not change the gravitational acceleration; it only affects the speed and time taken. D is wrong because energy conservation does not require a changing acceleration; in uniform gravity the acceleration remains constant while kinetic and potential energies interchange.

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