Lesson 2.4.1

2.4.1 Newton's third law and momentum Quiz: Pearson Edexcel Physics, Unit 2

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 2.4.1, Newton's third law and momentum: 20 multiple choice questions for the Pearson Edexcel Physics (9PH0), Unit 2: Mechanics, written with Revision Ninja.

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The 20 questions

  1. Newton's third law states that when body A exerts a force on body B, body B:

    • Exerts an equal and opposite force on body A.
    • Exerts a smaller force on body A.
    • Exerts a force on body A in the same direction.
    • Exerts no force on body A.

  2. Which statement describes a pair of forces in Newton's third law?

    • They are opposite in direction and cancel to zero resultant force on a body.
    • They are equal in magnitude and act on the same body.
    • They are equal in magnitude, opposite in direction, of the same type, and act on different bodies.
    • They are always different in type and act on the same body.

  3. Momentum is defined as:

    • p = mv
    • p = m/v
    • p = (1/2)mv^2
    • p = mv^2

  4. Momentum is best described as a:

    • Vector quantity in the direction of the velocity
    • Scalar quantity measured in joules
    • Vector quantity measured in newtons
    • Scalar quantity in the direction of force

  5. What is the momentum of a 0.2 kg ball moving at 5 m s^-1?

    • 2.5 kg m s^-1
    • 1.0 kg m s^-1
    • 25 kg m s^-1
    • 0.04 kg m s^-1

  6. A 1500 kg car travels at 20 m s^-1 due west. What is its momentum?

    • 75 kg m s^-1 west
    • 3.0 x 10^4 kg m s^-1 west
    • 3.0 x 10^4 kg m s^-2 west
    • 3.0 x 10^4 kg m s^-1 east

  7. A 2.0 kg gun recoils after firing a 0.010 kg bullet at 400 m s^-1. What is the recoil velocity of the gun?

    • 200 m s^-1 backwards
    • 0.02 m s^-1 backwards
    • 4.0 m s^-1 backwards
    • 2.0 m s^-1 backwards

  8. A 0.15 kg ball is thrown at 20 m s^-1 and bounces straight back at 15 m s^-1. What is the change in its momentum?

    • 5.3 kg m s^-1
    • 3.0 kg m s^-1
    • 0.75 kg m s^-1
    • 7.5 kg m s^-1

  9. The ball in the previous scenario is in contact with a wall for 0.050 s. What is the average force from the wall on it?

    • 0.26 N
    • 105 N
    • 5.25 N
    • 1050 N

  10. In a collision, body A exerts a force of 12 N on body B. What force does B exert on A?

    • 12 N in the opposite direction
    • 12 N in the same direction
    • 24 N in the opposite direction
    • 6 N in the opposite direction

  11. A 2.0 kg body moves at 3.0 m s^-1 east and a 4.0 kg body moves at 1.0 m s^-1 west. What is their total momentum?

    • 2.0 kg m s^-1 west
    • 2.0 kg m s^-1 east
    • 14 kg m s^-1 west
    • 10 kg m s^-1 east

  12. A student claims that equal and opposite forces in a collision must cancel, so nothing can move. What is the best response?

    • The forces cancel, so the student is right.
    • The forces act on different bodies, so they cannot cancel each other's effects on either body.
    • The forces act on the same body, so they add together.
    • Equal and opposite forces always cause the larger body to move.

  13. A car and a lorry collide. The forces they exert on each other are equal in size. Why do they have different accelerations?

    • The forces do not act at the same time.
    • The car has a larger momentum, so it accelerates less.
    • The lorry has a larger mass, so its acceleration from the same force is smaller.
    • The lorry exerts a larger force on the car.

  14. An apple of weight 0.2 N falls to the ground under gravity. What force does the apple exert on the Earth?

    • 9.8 N upwards
    • 0.2 N upwards
    • 0.2 N downwards
    • 0 N

  15. A 0.40 kg hockey puck moves at 15 m s^-1 north. What is its momentum?

    • 6.0 kg m s^-1 south
    • 6.0 kg m s^-1 north
    • 0.38 kg m s^-1 north
    • 15.4 kg m s^-1 north

  16. Two bodies have a total momentum of zero. Which statement must be true?

    • Their masses are equal.
    • Their momenta are equal in magnitude and opposite in direction.
    • Both bodies are at rest.
    • Their kinetic energies are zero.

  17. A rocket pushes exhaust gas backwards and moves forwards. Which explanation uses Newton's third law?

    • The gas has zero momentum, so the rocket must move forwards.
    • The rocket's weight pushes it forwards.
    • The gas pushes the rocket forwards with a force equal and opposite to the force the rocket exerts on the gas.
    • The gas pushes the rocket backwards with a larger force.

  18. A person pushes against a wall with a force of 50 N. What is the force of the wall on the person?

    • 25 N in the opposite direction
    • 50 N in the opposite direction
    • 100 N in the opposite direction
    • 50 N in the same direction

  19. A 1.0 kg trolley moves at 2.0 m s^-1 east. What is its momentum, and what is the direction of the momentum?

    • 1.0 kg m s^-1 east
    • 0.5 kg m s^-1 east
    • 2.0 kg m s^-1 east
    • 2.0 kg m s^-1 west

  20. Two bodies have equal and opposite momenta. What is the total momentum of the two-body system?

    • Equal to the sum of their speeds
    • Equal to the sum of their masses
    • Zero
    • Equal to twice one momentum

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