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Practice questions · Acceleration of free fall

Steady gain, every second.

Six original Cambridge-style questions on why g is constant and the same for all masses, the v = g t calculation, and the "acceleration keeps increasing" misconception.

Original questions All questions on this page are original work, written in the Cambridge IGCSE style. They are not from past papers. They test the same concepts and skills the syllabus rewards.
What to hold onto

g is fixed; velocity grows.

01
[2 marks]

State the approximate value of the acceleration of free fall near the Earth's surface, and state the assumption made when we say every object falls with this same value.

  • g ≈ 9.8 m/s² (10 m/s² is accepted). ✓
  • Assumption: air resistance is ignored (negligible). ✓
02
Analysis
[2 marks]

In a tall tube with the air removed, a feather and a coin are released together from the top. State what is observed and explain why.

  • They fall together and land at the same time. ✓
  • With no air resistance, both have the same acceleration g, which does not depend on mass. ✓
03
Calculation
[2 marks]

An object is dropped from rest. Taking g = 9.8 m/s² and ignoring air resistance, calculate its velocity after 4.0 s.

v = g t = 9.8 × 4.0

v = 39 m/s (39.2 m/s)

04
Analysis
[2 marks]

A student writes: "As the ball falls, it accelerates more and more." Ignoring air resistance, explain what is wrong and give the correct statement.

  • The acceleration does not increase; it stays constant at about 9.8 m/s². ✓
  • It is the velocity that increases, and it increases at a steady rate (by g each second). ✓
05
Calculation
[2 marks]

Taking g = 10 m/s², calculate the velocity of an object dropped from rest after 2.5 s.

v = g t = 10 × 2.5

v = 25 m/s

06
Analysis
[2 marks]

Describe the shape of the velocity-time graph for an object falling from rest with no air resistance, and state what its gradient represents.

  • A straight line through the origin (sloping upward). ✓
  • Its gradient represents the acceleration, which is constant and equal to g. ✓