Turning effects of forces: past paper questions
Real questions on turning effects of forces
The newest 20 of 27 written questions. Open one to see it on the real paper.
- 9702/22 · October/November 2025 · Q2a(i)[2]
Thruster A is activated, producing a force of 60 N upwards on the spacecraft. Thruster C is also activated, producing a force of 220 N in the leftwards direction on the spacecraft. Calculate the resultant moment due to these forces about the centre of gravity. resultant moment = N m
See it on the paper → - 9702/22 · October/November 2025 · Q2a(ii)[1]
State and explain whether the forces from A and C are a couple.
See it on the paper → - 9702/21 · May/June 2025 · Q2a[2]
State the principle of moments.
See it on the paper → - 9702/21 · May/June 2025 · Q2b[3]
A beam B C pivot x (b) Three objects A, B and C are placed on a horizontal beam. The beam is in equilibrium, as shown in Fig. 2.1. Calculate x. x = m The beam is uniform and has length 6.0 m. The pivot is at the midpoint of the beam. Object A has mass 60 kg and is at one end of the beam. Object B has mass 45 kg and is...
See it on the paper → - 9702/22 · May/June 2025 · Q2a[1]
Define the moment of a force about a point.
See it on the paper → - 9702/23 · May/June 2025 · Q2a[1]
Define the moment of a force about a pivot.
See it on the paper → - 9702/22 · February/March 2025 · Q2a[2]
State the principle of moments.
See it on the paper → - 9702/22 · February/March 2025 · Q2b(i)[3]
By taking moments about end A, determine the distance x from A to P. distance = m
See it on the paper → - 9702/23 · October/November 2024 · Q3a[1]
State the principle of moments.
See it on the paper → - 9702/23 · October/November 2024 · Q3b(i)[2]
Use the principle of moments to show that the upthrust U exerted by the water on the cylinder is 1.4 N.
See it on the paper → - 9702/22 · February/March 2023 · Q3c[2]
By taking moments about end A, calculate the weight W of the beam. W = N
See it on the paper → - 9702/23 · October/November 2022 · Q3a[2]
State the principle of moments.
See it on the paper → - 9702/23 · October/November 2022 · Q3b[2]
A hollow plastic sphere is attached at one end of a bar. The sphere is partially submerged in water and the bar is attached to a fixed vertical support by a pivot P, as shown in Fig. 3.1. 0.29 m P sphere, weight 0.30 N bar 40° fixed support surface of water Fig. 3.1 (not to scale) The sphere has weight 0.30 N. The dist...
See it on the paper → - 9702/23 · October/November 2022 · Q3c(iii)[2]
By taking moments about P, determine the force exerted on the spring by the rod R. force = N
See it on the paper → - 9702/22 · October/November 2020 · Q4a[1]
Show that the component of the weight that is perpendicular to the plank is 59 N.
See it on the paper → - 9702/22 · October/November 2020 · Q4b[3]
By taking moments about end A of the plank, calculate the tension T. T = N
See it on the paper → - 9702/23 · May/June 2020 · Q3a[2]
State the principle of moments.
See it on the paper → - 9702/23 · May/June 2020 · Q3b(i)[2]
By taking moments about end A, show that the weight W of each wheel is 14 N.
See it on the paper → - 9702/23 · May/June 2020 · Q3b(ii)[2]
Determine the magnitude and the direction of the force acting on the rod at end A. magnitude = N
See it on the paper → - 9702/43 · May/June 2020 · Q8c(i)[2]
Show that the change in moment of W about the pivot is 3.3 × 10 –5 N m.
See it on the paper →
What examiners said
There were very few fully correct answers. The candidates usually referred to the total clockwise moments being equal to the total anticlockwise moments. However, many candidates did not explicitly state that these moments are about the same point. It was also common for weaker candidates to omit ‘total’ from their answer. Only the stronger candidates stated that this was for an object in rotatio...
— Examiner report, February/March 2025, 9702/22 Q2(a) (Cambridge)
This part was generally well answered with many candidates obtaining the correct answer. Nearly all candidates could correctly determine one or two moments, but a significant number could not give all three moments. A common mistake was to think that the moment of the weight of the beam about end A was either (1700 6.0) N m or (1700 5.0) N m.
— Examiner report, February/March 2025, 9702/22 Q2(b)(i) (Cambridge)
In general, stronger candidates found it straightforward to determine the weight of the beam by applying the principle of moments. Weaker candidates often made a mistake in their calculation of one or two of the three moments about end A of the beam. A common error was to use the wrong distance when calculating the moment of the weight about end A.
— Examiner report, February/March 2023, 9702/22 Q3(c) (Cambridge)
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