Lesson 3.4.1.2

3.4.1.2 Moments Quiz: AQA Physics, Unit 4

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.4.1.2, Moments: 20 multiple choice questions for the AQA Physics (7408), Unit 4: Mechanics and materials, written with Revision Ninja.

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The 20 questions

  1. How is the moment of a force about a point defined?

    • Force × perpendicular distance from the point to the line of action of the force
    • Force × distance along the force
    • Force × mass
    • Force ÷ distance to the point

  2. What is a couple?

    • A single force acting through a pivot
    • Two forces acting along the same line
    • A pair of equal and opposite coplanar forces with different lines of action
    • Two forces of different sizes acting at different points

  3. How is the moment of a couple defined?

    • Force × distance from the pivot to one force
    • Force ÷ perpendicular distance
    • Force × mass
    • Force × perpendicular distance between the lines of action

  4. What does the principle of moments state for an object in equilibrium?

    • Moments are always zero
    • The sum of forces is always greater than the sum of moments
    • The sum of clockwise moments equals the sum of anticlockwise moments
    • Clockwise moments are always larger

  5. Where is the centre of mass of a uniform regular solid?

    • At its highest point
    • At its geometric centre
    • At one of its corners
    • At the base

  6. What is the unit of moment?

    • kg m
    • N/m
    • N m
    • N s

  7. A force of 4.0 N acts at a perpendicular distance of 0.30 m from a pivot. What is its moment?

    • 1.2 N m
    • 0.075 N m
    • 13 N m
    • 4.3 N m

  8. A seesaw has a 300 N load 1.0 m from the pivot. What distance from the pivot balances a 200 N load on the other side?

    • 1.5 m
    • 0.5 m
    • 2.0 m
    • 0.67 m

  9. A uniform beam of weight 100 N and length 4 m is pivoted at its left end. What is the moment of its weight about the pivot?

    • 50 N m
    • 200 N m
    • 100 N m
    • 400 N m

  10. Two 5 N forces act in opposite directions 0.2 m apart as a couple. What is the moment?

    • 1.0 N m
    • 0.04 N m
    • 10 N m
    • 2.5 N m

  11. Why is the moment of a couple the same about any point?

    • The forces cancel to zero moment
    • The moment is always zero
    • The pivot always lies between the forces
    • Its net force is zero, so only the separation of the two lines of action matters

  12. A 40 N force acts at 30 degrees to a spanner of length 0.25 m. What is the moment about the bolt?

    • 10 N m
    • 2.5 N m
    • 8.7 N m
    • 5.0 N m

  13. Two masses of 2 kg at 0 m and 3 kg at 1 m lie along a line. Where is their combined centre of mass?

    • 0.4 m
    • 0.6 m
    • 1.0 m
    • 0.5 m

  14. A 0.5 kg mass hangs 0.3 m left of the pivot on a uniform rule. What mass hung 0.3 m right of the pivot balances it?

    • 0.25 kg
    • 0.15 kg
    • 0.5 kg
    • 1.0 kg

  15. A 600 N person sits 1.5 m from the pivot of a seesaw. A 900 N person is on the other side. At what distance do they balance?

    • 0.67 m
    • 1.0 m
    • 2.25 m
    • 1.5 m

  16. Why must a force's moment use the perpendicular distance to its line of action?

    • The distance along the force is always zero
    • Perpendicular distances are always shorter
    • Only the component of the force perpendicular to the lever arm produces a turning effect
    • Forces only act perpendicular to the lever

  17. Why does a wide-based object tend to be more stable?

    • It has more mass
    • Its centre of mass is lower and its line of action falls within a wider base
    • Its weight is smaller
    • Friction is greater on a wide base

  18. If a body is in equilibrium, what is the net moment about any point?

    • the total weight
    • the mass times the length
    • unchanged from before
    • zero

  19. A 2.0 N weight hangs 0.2 m left of a pivot. What distance right of the pivot must a 0.5 N weight hang to balance it?

    • 0.2 m
    • 0.08 m
    • 0.5 m
    • 0.8 m

  20. A student says the moment equals force times the distance from the pivot to the point of application. What is the correction?

    • The distance must be measured from the centre of mass
    • The moment is force divided by distance
    • Only forces in the same direction count
    • The perpendicular distance to the line of action of the force is needed

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