About Dynamics in A Level Physics
Dynamics is one of the 13 main topics in our A Level Physics (Cambridge (CAIE) 9702) question bank, and about 8% of its real questions come from it. Tayyari Karo has 54 real questions on this topic from 2021 to 2026, from Paper 1, Paper 2; 47 are multiple choice and marked instantly, and the rest are structured questions with a model answer. By difficulty: 28 medium, 16 hard, 10 easy.
Work through the questions below, then open the explanation for each one. Redo the ones you missed a few days later.
Try 6 real questions
These are real past-paper questions. Think of your answer first, then open the explanation.
May/June 2026 · Paper 1 · Dynamics
The mass of a fully grown African elephant is approximately four times the mass of an average car. The maximum speed of an African elephant is 40 km per hour.
What is a reasonable estimate of the maximum momentum of a fully grown African elephant?
- 5 × 10³ kg m s⁻¹
- 7 × 10⁴ kg m s⁻¹
- 9 × 10⁵ kg m s⁻¹
- 2 × 10⁶ kg m s⁻¹
Show answer and explanation
Answer: B. 7 × 10⁴ kg m s⁻¹
A car is about 1200-1500 kg, so the elephant is about 5000-6000 kg; 40 km/h ≈ 11 m s⁻¹; p ≈ 6 × 10⁴, closest to 7 × 10⁴ kg m s⁻¹.
October/November 2025 · Paper 1 · Dynamics
An object of mass m moving with velocity 9.0 m s⁻¹ has a head-on elastic collision with a stationary object of mass 2m. After the collision, both objects are moving. No external forces act on the system. What is the velocity of the object of mass 2m after the collision?
- −6.0 m s⁻¹
- −3.0 m s⁻¹
- 4.5 m s⁻¹
- 6.0 m s⁻¹
Show answer and explanation
Answer: D. 6.0 m s⁻¹
For an elastic collision, v2' = 2m1u1/(m1+m2) = 2m(9.0)/3m = 6.0 m s⁻¹.
October/November 2024 · Paper 1 · Dynamics
A car of mass 1200 kg has momentum 18 000 kg m s⁻¹.
What is the kinetic energy of the car?
- 4.65 kJ
- 6.57 kJ
- 135 kJ
- 270 kJ
Show answer and explanation
Answer: C. 135 kJ
v = p/m = 15 m s⁻¹; KE = p²/2m = 18000²/(2×1200) = 135 000 J.
May/June 2023 · Paper 1 · Dynamics
The driver of a car applies two parallel forces, each of magnitude 15 N, to a steering wheel of diameter 0.40 m. Each force acts at 65° to the horizontal diameter of the wheel, at opposite ends of that diameter, forming a couple. What is the torque exerted on the steering wheel?
- 1.3 N m
- 2.5 N m
- 2.7 N m
- 5.4 N m
Show answer and explanation
Answer: D. 5.4 N m
Each force's perpendicular component = 15 sin65° = 13.6 N; torque of couple = 2 × 13.6 × 0.20 ≈ 5.4 N m.
October/November 2023 · Paper 1 · Dynamics
In an experiment, a metal ball is dropped into a viscous liquid and its terminal velocity is measured. The experiment is repeated, each time changing one of: 1 the density of the metal of the ball, 2 the height from which the ball is dropped, 3 the density of the liquid, 4 the depth of the liquid.
Which two changes separately affect the terminal velocity of the ball in the liquid?
- 1 and 2
- 1 and 3
- 2 and 4
- 3 and 4
Show answer and explanation
Answer: B. 1 and 3
At terminal velocity, weight = upthrust + viscous drag; both depend on the density of the ball (weight) and the density of the liquid (upthrust), but not on the drop height or liquid depth (once terminal velocity is reached).
October/November 2022 · Paper 1 · Dynamics
A mass of 0.20 kg is suspended from the lower end of a light spring. A second mass of 0.10 kg is suspended from the first mass by a thread. The arrangement is in static equilibrium and then the thread is cut.
Immediately after the thread is cut, what is the upward acceleration of the 0.20 kg mass?
- 4.9 m s⁻²
- 6.5 m s⁻²
- 9.8 m s⁻²
- 15 m s⁻²
Show answer and explanation
Answer: A. 4.9 m s⁻²
Spring tension before cutting = (0.30)(9.81) = 2.943 N (unchanged instantaneously). Net force on 0.20 kg mass = 2.943 − (0.20×9.81) = 0.981 N, so a = 0.981/0.20 ≈ 4.9 m s⁻².
