AQA GCSE Physics Physics Paper 2 (Higher), June 2023: Question 5
10 marks · Standard Demand difficulty · Short Answer
Analyze bumper car collisions involving closed systems, Newton's Third Law, momentum calculations, force reduction via flexible bumpers, and SUVAT equations.
Practise this questionQuestion
Question text
05 Figure 14 shows some bumper cars.
Bumper cars are designed to withstand collisions at low speeds.
Figure 14
05.1 During a collision between a bumper car and the barrier, the bumper car and barrier
act as a closed system.
What is meant by a ‘closed system’?
[1 mark]
05.2 How does Newton’s Third Law of motion apply to the collision between the
bumper car and the barrier?
[1 mark]
05.3 During the collision, the change in momentum of the bumper car is 700 kg m/s.
*24* The time taken for the collision is 0.28 s.
Calculate the force on the bumper car during the collision.
Use the Physics Equations Sheet.
[2 marks]
26 Force = N
05.4 The bumper car has a flexible bumper.
Explain how the flexible bumper reduces the risk of injury to the people in the
bumper car during the collision.
[3 marks]
*0255.*5 A bumper car moved with an initial constant velocity and then accelerated
at 2.0 m/s2.
While accelerating, the bumper car travelled a distance of 1.5 m.
The final velocity of the bumper car was 2.5 m/s.
Calculate the initial constant velocity of the bumper car.
Use the Physics Equations Sheet.
[3 marks]
Initial constant velocity = m/s
Mark scheme
Show the mark scheme
Question 5
AO /
Question Answers Extra information Mark
Spec. Ref.
05.1 the total amount of energy (of 1 AO1
the bumper car and barrier) 4.5.7.2
remains constant. 4.1.2.1
or
total momentum (of bumper car
and barrier) before collision
equals total momentum (of
bumper car and barrier) after
collision
or
the resultant external force allow there are no external
acting (on the system) is zero forces (acting on the system)
AO /
Spec. Ref.
05.2 the force of the car on the 1 AO1
barrier is equal to the force of 4.5.6.2.3
the barrier on the car and in the
opposite direction
AO /
Spec. Ref.
05.3 700 1 AO2
F =
0.28 4.5.7.3
F = 2 500 (N) – HYSICS – 1 –
AO /
Spec. Ref.
05.4 increases the time taken for the allow increases contact time 1 AO1
collision to occur do not accept slows down time 4.5.7.3
(so) the rate of change of allow reduces acceleration / 1
momentum decreases deceleration
reducing the force (on the reduces impact is insufficient 1
people)
AO /
Spec. Ref.
05.5 2.52 – u2 = 2 × 2.0 × 1.5 1 AO2
4.5.6.1.5
u2 = 2.52 – (2 × 2.0 × 1.5) 1
u = 0.50 (m/s) allow 0.5 (m/s) 1
Total Question 5 10
How to answer it
Forces, Momentum & Motion Study Guide
What this question tests
This question assesses your understanding of momentum, Newton's Third Law, closed systems, safety features involving force and time, and kinematic equations of motion. You will need to recall key definitions, apply formulae correctly, and show clear step-by-step calculation working.
Defining a Closed System
✅ Correct Answer
Any one of the following points:
- The total amount of energy of the bumper car and barrier remains constant.
- The total momentum before the collision equals the total momentum after the collision.
- The resultant external force acting on the system is zero (no external forces).
💡 Key Knowledge
A closed system is a physical system that doesn't exchange any matter with its surroundings and isn't subject to any net external force. In collisions, total momentum is always conserved within a closed system.
Newton's Third Law in Collisions
✅ Correct Answer
The force of the car on the barrier is equal to the force of the barrier on the car, and acts in the opposite direction.
🧠 Exam Technique
When quoting Newton's Third Law, you must reference two objects interacting, equal magnitude, and opposite direction. Avoid vague phrases like "every action has an equal and opposite reaction" without linking it directly to the car and barrier.
Calculating Force from Momentum Change
📐 Step-by-Step Calculation
Formula: Force = Change in momentum / time (F = Δp / Δt)
- Identify values: Change in momentum = 700 kg m/s , Time = 0.28 s .
- Substitute into equation: F = 700 / 0.28
- Calculate final value: 2500 N
❌ Common Errors
Students sometimes accidentally multiply the momentum change by the time instead of dividing, or invert the fraction. Always check your units: kg m/s divided by s gives Newtons ( N ).
Flexible Bumpers & Safety
✅ Correct Answer
- It increases the time taken for the collision to occur (contact time).
- Therefore, the rate of change of momentum decreases (or deceleration is reduced).
- This reduces the force on the people inside the car.
❌ Common Errors
Examiners note that saying "reduces impact" is too vague and insufficient for the final mark. You must explicitly link the increased time to a reduced rate of momentum change and smaller force.
Calculating Initial Velocity (Kinematics)
📐 Step-by-Step Calculation
Formula: v² - u² = 2as
- Identify variables: v = 2.5 m/s , a = 2.0 m/s² , s = 1.5 m , u = ?
- Substitute values: 2.5² - u² = 2 × 2.0 × 1.5
- Simplify numbers: 6.25 - u² = 6.0
- Rearrange for u²: u² = 6.25 - 6.0 = 0.25
- Square root: u = √(0.25) = 0.50 m/s
🧠 Exam Technique
This is a multi-step rearrangement question worth 3 marks. One mark is awarded for correct substitution into the equations of motion formula, one for rearranging correctly, and the final mark for the correct numerical answer with proper units.
Topics
Physics · P1: Energy · P5: Forces
Question and mark scheme from the AQA GCSE Physics examination, Physics Paper 2 (Higher), June 2023. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.