IGCSE · Physics 0625 · Motion, forces & energy

Pendulums & timing: IGCSE Physics questions with answers

Free Pendulums & timing questions for IGCSE Physics (0625), part of Motion, forces & energy. Each question has the answer and the marking points an examiner would look for.

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Pendulums & timing practice questions

Question 1Multiple choice · 1 markA* challenge

A student starts a stopwatch as a pendulum bob passes through the centre of its swing. She stops it when the bob passes through the centre for the 40th time after that. The stopwatch reads 16.8 s.
What is the period of the pendulum?

  1. A 0.410 s
  2. B 0.420 s
  3. C 0.840 s
  4. D 1.68 s
Show answer

Answer: C

Question 2Multiple choice · 1 markA* challenge

A student uses a fiducial (reference) marker at the centre of a pendulum’s swing.
Why?

  1. A The bob stops there.
  2. B It reduces air resistance.
  3. C It makes the period longer.
  4. D The bob moves fastest there, so timing is most precise.
Show answer

Answer: D

Question 3Multiple choice · 1 mark

How can the period of a simple pendulum be increased?

  1. A increase the length of the string
  2. B decrease the length of the string
  3. C swing it with a smaller amplitude
  4. D increase the mass of the bob
Show answer

Answer: A

Question 4Multiple choice · 1 mark

Why does a student time 20 oscillations of a pendulum rather than one?

  1. A to increase the amplitude
  2. B to keep the length constant
  3. C to reduce the effect of reaction time on the measured period
  4. D to increase the period
Show answer

Answer: C

Question 5Multiple choice · 1 markA* challenge

A student starts a stopwatch as a pendulum bob passes through the centre of its swing. She stops it when the bob passes through the centre for the 20th time after that. The stopwatch reads 16.8 s.
What is the period of the pendulum?

  1. A 0.800 s
  2. B 0.840 s
  3. C 1.68 s
  4. D 3.36 s
Show answer

Answer: C

Question 6Structured · 8 marks

A student investigates a simple pendulum of length 0.60 m.

(a)

Explain why the student times 20 complete oscillations rather than one.

[2]
(b)

The time for 20 oscillations is 31.1 s. Calculate the period.

[1]
(c)

Describe how a fiducial marker helps the student time the oscillations.

[1]
(d)

Describe the energy changes during one swing from one side to the lowest point.

[2]
(e)

The bob rises 5.0 cm above its lowest point. Calculate its speed at the lowest point.

[2]
Show answers and mark scheme
PartAnswer and marking pointsMarks
(a)reduces the effect of reaction time; more accurate
reduces the percentage uncertainty B1
caused by reaction time when starting and stopping the stopwatch B1
2
(b)1.55 s
31.1/20 = 1.55 s B1
1
(c)mark at the centre of the swing to start and stop timing
a marker at the lowest point / centre of the swing gives a clear reference point for counting oscillations B1
1
(d)gravitational potential → kinetic
gravitational potential energy decreases B1
kinetic energy increases (maximum at the lowest point) B1
2
(e)0.990 m/s
½mv² = mgh, v = √(2 × 9.8 × 0.050) C1
0.990 m/s A1
2

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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