Lesson R4

R4 Newton's third law and equilibrium Quiz: AQA Maths, Unit 12

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson R4, Newton's third law and equilibrium: 20 multiple choice questions for the AQA Maths (7357), Unit 12: Mechanics, written with Revision Ninja.

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The 20 questions

  1. According to Newton's third law, if object A exerts a force on object B, what force does B exert on A?

    • Smaller and opposite
    • Equal and opposite
    • Larger and opposite
    • Equal and same direction

  2. On which bodies do the forces in a Newton's third law action-reaction pair act?

    • The same body
    • Different bodies
    • Adjacent particles
    • Opposite directions

  3. Which force forms a Newton's third law pair with a book's weight?

    • Table pushing book
    • Normal reaction force
    • Book pulling Earth
    • Frictional contact force

  4. What is the magnitude of the resultant force acting on a particle in equilibrium?

    • Equal to mass
    • Zero
    • Greater than weight
    • Constant

  5. What is true about the tension throughout a light, inextensible string over a smooth pulley?

    • It varies with acceleration
    • It is constant
    • It is zero
    • It increases downwards

  6. Particles A (3 kg) and B (2 kg) are connected by a light inextensible string over a smooth pulley, with A hanging. With g = 10 m s^-2, what is the acceleration?

    • 2 m s^-2
    • 0.2 m s^-2
    • 5 m s^-2
    • 10 m s^-2

  7. For the system in the previous question (A 3 kg, B 2 kg, g = 10 m s^-2), what is the tension in the string?

    • 30 N
    • 24 N
    • 12 N
    • 20 N

  8. A particle is in equilibrium under forces 10 N west, 6 N north and a third force F. What is the magnitude of F, to 1 decimal place?

    • 8.0 N
    • 4.0 N
    • 11.7 N
    • 16.0 N

  9. Forces of 6 N and 8 N act at right angles on a particle in equilibrium with a third force. What is the magnitude of the third force?

    • 8 N
    • 14 N
    • 10 N
    • 2 N

  10. For a particle in equilibrium, what is the sum of resolved force components in any direction?

    • Dependent on angle
    • Equal to weight
    • Zero
    • Maximum

  11. A 20 N force acts at 60 degrees above the horizontal. What is its vertical component, to 1 decimal place?

    • 10.0 N
    • 17.3 N
    • 20.0 N
    • 34.6 N

  12. A particle of weight 40 N on a horizontal table is pulled by a string at 30 degrees above the horizontal with tension 10 N. What is the normal reaction from the table?

    • 35 N
    • 45 N
    • 40 N
    • 30 N

  13. Masses of 5 kg and 3 kg are connected by a light string over a smooth pulley and released, with g = 10 m s^-2. What is the acceleration?

    • 5 m s^-2
    • 2.5 m s^-2
    • 2 m s^-2
    • 0.25 m s^-2

  14. A 4 kg particle A on a smooth horizontal table is connected by a light string to a 2 kg particle B on the same table. A horizontal force of 12 N pulls A away from B. What is the tension in the string?

    • 8 N
    • 4 N
    • 12 N
    • 2 N

  15. A person exerts a 200 N force on a wall. What force does the wall exert on the person?

    • 100 N
    • 200 N
    • 0 N
    • 400 N

  16. A particle is in equilibrium under forces (2i + j) N, (-i + 3j) N and F. What is F?

    • 3i + 4j N
    • i + 4j N
    • -3i - 4j N
    • -i - 4j N

  17. A light inextensible string passes over a smooth pulley, connecting a 4 kg particle on a smooth horizontal table to a hanging 6 kg particle. With g = 10 m s^-2, what is the acceleration?

    • 2.4 m s^-2
    • 10 m s^-2
    • 4 m s^-2
    • 6 m s^-2

  18. For the system in the previous question (4 kg on a smooth table, 6 kg hanging, g = 10 m s^-2), what is the tension?

    • 24 N
    • 16 N
    • 40 N
    • 60 N

  19. What shape is formed when three coplanar forces keeping a particle in equilibrium are drawn tip-to-tail?

    • An open line
    • A closed triangle
    • A rectangle
    • A right angle

  20. Two particles of masses 6 kg and 4 kg are connected by a light string over a smooth pulley, with the 6 kg hanging. With g = 10 m s^-2, what is the tension?

    • 40 N
    • 48 N
    • 24 N
    • 60 N

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