AQA AS Level Physics Paper 2, June 2022: Question 16

1 mark · Medium difficulty · Multiple Choice

Calculate the length of a pulse created on a long spring given the time taken to generate it and the speed at which it travels.

Practise this question

Question

A multiple choice question featuring a diagram of a spring lying horizontally on a table attached to a wall at one end. A hand moves the free end to create a pulse, with the text giving the movement time as 0.40 s and the pulse travel distance as 4.0 m in 2.0 s. Four options are provided: A 0.8 m, B 1.6 m, C 2.0 m, and D 10.0 m.
Question text

16 A long spring is used to demonstrate wave motion. The spring lies horizontally on a table.

One end of the spring is attached to a wall.

The free end of the spring is quickly moved to one side and then back to the centre,

creating a pulse.

This movement takes 0.40 s.

The pulse travels 4.0 m along the spring in a time of 2.0 s.

What is the length of the pulse?

[1 mark]

A 0.8 m

B 1.6 m

C 2.0 m

D 10.0 m

Mark scheme

Show the mark scheme The mark scheme table indicates that the correct answer is option A, corresponding to 0.8 m.

16 A (AO2) 0.8 m

How to answer it

Calculating the Length of a Wave Pulse

AQA AS Level Physics • Waves

What this question tests

This question assesses your understanding of wave kinematics, specifically the relationship between wave speed, distance, time, and the spatial length (extent) of a travelling wave pulse generated over a known time interval.

Question 16: Multiple Choice Analysis

Determining the physical length of a generated pulse

✅ Correct Answer

A (0.8 m)

Marks available: 1 mark (AO2)

💡 Key Knowledge

  • Wave Speed Formula: v = d / t (Speed = Distance / Time).
  • Pulse Duration: The time taken to create the pulse represents the duration of the disturbance ( 0.40 s ).
  • Spatial Extent: The physical length of the pulse in space equals the distance the wave travels during the time it takes to create it.

📐 Step-by-Step Calculation

  1. Find the speed of the wave pulse:
    v = 4.0 m / 2.0 s = 2.0 m s⁻¹
  2. Calculate the length of the pulse:
    Length = speed × duration to create pulse
    Length = 2.0 m s⁻¹ × 0.40 s = 0.80 m (rounds/matches option A: 0.8 m )

🧠 Exam Technique

Always separate the motion of the wave travelling along the spring ( 4.0 m in 2.0 s ) from the time it takes the hand to generate the individual pulse ( 0.40 s ). Use the calculated wave speed as a bridge between time and space.

❌ Common Errors

  • Dividing the total distance ( 4.0 m ) by the creation time ( 0.40 s ), confusing the propagation speed with the source parameters.
  • Multiplying incorrect time and distance pairs together due to misreading the stem of the question.

Topics

Physics · 3.3 Waves

Question and mark scheme from the AQA AS Level Physics examination, Paper 2, June 2022. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.