Free Dynamics questions for AS Level Physics (9702), part of Mechanics & materials. Each question has the answer and the marking points an examiner would look for.
Generate a full Dynamics worksheet →All Mechanics & materials questionsA book rests on a table on the Earth.
1 The normal contact force on the book is equal to its weight because of Newton’s third law.
2 The forces in a Newton’s third law pair are always of the same type.
3 The pull of the Earth on the book and the pull of the book on the Earth are a Newton’s third law pair.
Which statements are correct?
Answer: B
A force of 50 N acts on a body for 0.20 s. What is the impulse?
Answer: B
Which term is described by this statement?
“The resultant force is proportional to the rate of change of momentum.”
Answer: D
Trolley A of mass 0.3 kg moves at 5.0 m s−1 towards stationary trolley B of mass 0.6 kg on a frictionless track. After the collision A rebounds at 0.5 m s−1.
State the principle of conservation of momentum.
Calculate the velocity of B after the collision.
Determine, using relative speeds, whether the collision is elastic.
The collision lasts 0.05 s. Calculate the average force exerted on A, and state its direction.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | total momentum of a system remains constant provided no resultant external force acts sum of momenta constant / momentum before = after B1 for a closed system / no resultant external force B1 | 2 |
| (b) | 2.75 m s−1 0.3 × 5 = 0.3 × (−0.5) + 0.6v C1 2.75 A1 | 2 |
| (c) | speed of approach 5 m s−1; speed of separation 3.25 m s−1; not equal, so inelastic both relative speeds calculated M1 inelastic A1 | 2 |
| (d) | 33 N opposite to A’s original motion Δp = 0.3 × 5.5 C1 33 N, direction opposite to initial velocity A1 | 2 |
A sphere A of mass 0.40 kg moving at 3.0 m s−1 collides head-on with a stationary sphere B of mass 0.30 kg. After the collision B moves at 3.43 m s−1.
State the principle of conservation of momentum.
Calculate the velocity of A after the collision, stating its direction.
Use relative speeds to show that the collision is elastic.
The collision lasts 0.050 s. Calculate the average force exerted by A on B.
State Newton’s third law and use it to state the average force exerted by B on A.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | total momentum of a system constant if no resultant external force the total momentum of a system remains constant B1 provided no resultant external force acts on the system B1 | 2 |
| (b) | 0.429 m s−1 in the original direction 0.40 × 3.0 = 0.40v + 0.30 × 3.43 C1 v = 0.429 m s−1 A1 direction stated A1 | 3 |
| (c) | relative speed of approach = relative speed of separation speed of approach = 3.0 m s−1 C1 speed of separation = 3.00 m s−1, equal so elastic A1 | 2 |
| (d) | 20.6 N F = Δp/Δt = 0.30 × 3.43/0.050 C1 20.6 N A1 | 2 |
| (e) | equal and opposite forces on different bodies; same magnitude opposite direction if body A exerts a force on body B, B exerts an equal and opposite force on A B1 20.6 N in the opposite direction B1 | 2 |
A ball falls vertically through air and reaches terminal velocity.
Describe and explain how the acceleration of the ball changes.
State the condition for an object to be in equilibrium.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | decreases from g to zero as drag increases initially acceleration is g B1 drag increases with speed so resultant force decreases B1 acceleration decreases to zero at terminal velocity B1 | 3 |
| (b) | resultant force and moment zero no resultant force and no resultant moment B1 | 1 |
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Meet Riyaz →Original Cambridge-style practice questions written for mentorriyaz.in. These are not Cambridge past paper questions, and this site is not affiliated with or endorsed by Cambridge University Press & Assessment. Updated 2026-11-04. Paper generator · mentorriyaz.in