Lesson 3.03h

3.03h Newton's third law Quiz: OCR Maths, Unit 18

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.03h, Newton's third law: 20 multiple choice questions for the OCR Maths (H240), Unit 18: Forces and Newton's Laws, written with Revision Ninja.

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The 20 questions

  1. According to Newton's third law, action and reaction forces are equal in magnitude and what?

    • Same in direction
    • Opposite in direction
    • Perpendicular in direction
    • Double in magnitude

  2. According to Newton's third law, action and reaction forces always act on how many distinct bodies?

    • Four bodies
    • Two bodies
    • One body
    • Three bodies

  3. What force acts perpendicular to the surface at the point of contact between two bodies?

    • Tension force
    • Gravitational force
    • Frictional force
    • Normal reaction force

  4. What condition indicates that a body has lost contact with a supporting surface?

    • Acceleration is zero
    • Reaction is maximum
    • Reaction is zero
    • Velocity is zero

  5. In mechanics, what does modelling a contact surface as smooth imply about friction?

    • Friction is maximum
    • Friction is zero
    • Friction is constant
    • Friction is variable

  6. An object of weight W rests on a horizontal table. What magnitude is the normal reaction?

    • 0.5W
    • Zero
    • W
    • 2W

  7. A system of components with no relative motion can be modelled as what?

    • A single particle
    • A smooth pulley
    • A rigid beam
    • Multiple light strings

  8. If particle A exerts a force F on particle B, what force does B exert on A?

    • 2F
    • -F
    • Zero
    • 0.5F

  9. A particle is in equilibrium if and only if the sum of resolved components in any direction is what?

    • Equal to mass
    • Zero
    • Equal to gravity
    • Constant

  10. What is the normal reaction on a 5 kg mass resting on a flat horizontal surface?

    • 50 N
    • 9.8 N
    • 49 N
    • 5 N

  11. When resolving forces on an inclined plane, forces are typically resolved parallel and how else?

    • Horizontally
    • Perpendicular to plane
    • Parallel to gravity
    • Vertically

  12. Why do internal tension forces cancel out when analysing a system of connected particles as one?

    • Conservation of energy
    • Hooke's law
    • Newton's third law
    • Newton's first law

  13. A 2 kg mass rests on a smooth plane inclined at 30 degrees. What is the normal reaction?

    • 39.2 N
    • 17 N
    • 19.6 N
    • 9.8 N

  14. A 10 N horizontal force pulls two connected masses totaling 5 kg on a smooth surface. What is acceleration?

    • 2 m/s^2
    • 5 m/s^2
    • 50 m/s^2
    • 0.5 m/s^2

  15. What component of weight acts down a smooth 30 degree incline for a 3 kg mass?

    • 29.4 N
    • 14.7 N
    • 9.8 N
    • 25.5 N

  16. A vertical upward force of 40 N acts on a 10 kg mass on a horizontal floor. What is R?

    • 40 N
    • 138 N
    • 58 N
    • 98 N

  17. A lift of total mass 400 kg accelerates upwards at 2 m/s^2. What is the tension in the lift cable?

    • 800 N
    • 4720 N
    • 3120 N
    • 3920 N

  18. What assumption allows us to treat tension as constant throughout a connecting string?

    • String is smooth
    • String is rigid
    • String is elastic
    • String is light

  19. What happens to a particle when the calculated normal reaction force R becomes negative?

    • It accelerates downwards
    • Friction increases
    • It leaves surface
    • It stops moving

  20. Two masses of 3 kg and 1 kg are connected over a smooth pulley. What is their acceleration?

    • 2.45 m/s^2
    • 19.6 m/s^2
    • 9.8 m/s^2
    • 4.9 m/s^2

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