Lesson T2.3.1

T2.3.1 Balanced forces and equilibrium Quiz: KS3 Physics, Unit 2

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson T2.3.1, Balanced forces and equilibrium: 20 multiple choice questions for the KS3 Physics (National Curriculum), Unit 2: Motion and forces, written with Revision Ninja.

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The 20 questions

  1. What is the resultant force when two balanced forces act on an object?

    • Twice the smaller of the two forces, because the two forces add together in the same line
    • Equal to the sum of the two forces, because the forces combine when they act on one object
    • Zero
    • Equal to the larger of the two forces, because the larger force always wins the contest

  2. An object is in equilibrium. What does this mean?

    • It is moving faster than it was a moment before, because the forces have sped it up slightly.
    • The forces acting on it are balanced, so its resultant force is zero.
    • Only its weight is acting on it, pulling it straight down towards the centre of the Earth.
    • No forces are acting on it at all, so it is free from every push and pull in its surroundings.

  3. A book at rest on a table has a weight of 10 N downwards and the table pushes it up with 10 N. What is the resultant force on the book?

    • 20 N upwards, which is found by adding the weight and the upward push of the table together
    • 10 N downwards, which is the weight of the book acting on its own with no upward force
    • 0 N
    • 5 N upwards, which is found by halving the upward push of the table on the book

  4. A mass hangs at rest from a spring. What force does the spring exert on the mass?

    • A force of zero, because the mass is not moving at any point while it hangs at rest.
    • A force greater than the weight of the mass, acting downwards to pull the mass lower still.
    • A force equal to twice the weight of the mass, acting downwards and stretching it further.
    • A force equal to the weight of the mass, acting upwards.

  5. What happens to an object when balanced forces act on it?

    • It speeds up steadily in the direction of its motion, because the forces push it forward together.
    • It keeps the same velocity, so a stationary object stays still.
    • It stops immediately, because the forces that act on it cancel out and remove its motion entirely.
    • It accelerates in a circle around a fixed point, because balanced forces always cause circular motion.

  6. A force of 8 N acts to the east and a force of 3 N acts to the west on the same object. What is the resultant force?

    • 5 N to the west, which points the resultant in the direction of the smaller force instead
    • 11 N to the east, which is found by adding the two forces together even though they oppose
    • 8 N to the west, which keeps the larger force but reverses its direction for the answer
    • 5 N to the east

  7. Two tug-of-war teams each pull on a rope with 300 N in opposite directions. What is the resultant force on the rope?

    • 150 N, which is half of one team's pull, shared out between the two opposing teams
    • 0 N
    • 600 N, which is found by adding the two pulls together as if both acted in the same direction
    • 300 N, which is the pull from one team alone, ignoring the pull from the opposing team

  8. An object has forces of 12 N upwards and 7 N downwards acting on it, with no other forces. What is the resultant force?

    • 5 N downwards, which points the resultant in the direction of the smaller force instead
    • 5 N upwards
    • 16 N downwards, which subtracts the larger force from the sum of the two forces wrongly
    • 19 N upwards, which is found by adding the two forces together even though they oppose

  9. A 2 N weight hangs at rest from a spring. What is the tension force in the spring?

    • 4 N upwards, which is found by doubling the weight because the spring is stretched twice
    • 1 N upwards, which is found by halving the weight because the spring shares the load
    • 2 N upwards
    • 2 N downwards, which points the tension force in the same direction as the weight below it

  10. What does the length of a force arrow drawn in a diagram represent?

    • The length of time for which the force acts on the object, shown as a length of arrow
    • The mass of the object the force acts on, scaled up for a clearer picture of the situation
    • The size (magnitude) of the force
    • The speed of the object at the moment shown, with faster objects drawn with longer arrows

  11. A book rests on a table. What provides the upward force that holds the book up?

    • Air pushing the book upwards from below, which holds it up against its own weight
    • Gravity pulling the book upwards, which is the force that keeps it balanced on the surface
    • The book's own weight pushing upwards, which lifts it against the pull of the table
    • The table pushing up on the book

  12. A 15 N object is in equilibrium and is supported by two upward forces. One of the supports provides 9 N. What is the other support force?

    • 12 N, which is found by taking the difference between the weight and half of the first support
    • 24 N, which is found by adding the two supports together and then adding the weight again
    • 6 N
    • 9 N, which assumes the two supports must provide the same force as each other at all times

  13. What must be true of the resultant force for an object to keep moving at a constant velocity?

    • It must be as large as the object's weight, so that the object is supported at all times
    • It must point in the direction of motion, so that the object keeps accelerating forwards
    • It must be zero.
    • It must be greater than the object's mass, so the object keeps moving in a straight line

  14. A car travels at a steady speed on a flat road. The engine provides a forward force of 800 N. What is the size and direction of the resistance force?

    • No resistance at all, because a car travelling at steady speed does not need any opposing force
    • 1600 N backwards, which assumes the resistance force is twice the forward force of the engine
    • 400 N backwards, which assumes that friction alone supplies half of the balancing force needed
    • 800 N backwards, from friction and air resistance

  15. A box that is already moving is pushed with a force of 40 N while friction of 40 N acts against it. What happens to its motion?

    • It accelerates opposite to the push, because the friction is the larger of the two forces in play.
    • It accelerates in the direction of the push, because the push is the only force that is acting on it.
    • It accelerates upwards off the surface, because the push lifts the box clear of the ground.
    • It keeps moving at a constant velocity.

  16. An object sits still with a 20 N force acting to the right and a 20 N force acting to the left. Which best describes the object?

    • It is accelerating to the right, because the force on the right is applied slightly later in time.
    • It is gaining mass while the forces act on it, because the forces add weight to the object.
    • It is in equilibrium, with no change to its motion.
    • It is accelerating to the left, because the force on the left pulls the object in that direction.

  17. A force of 30 N and a force of 50 N act on an object in the same direction. What is the resultant force?

    • 1500 N, which is found by multiplying the two forces together, which is not how forces combine
    • 80 N
    • 40 N, which is found by taking the average of the two forces acting on the object
    • 20 N, which is found by subtracting the smaller force from the larger one as if they opposed

  18. A trolley moving to the right has a 5 N force to the right and a 5 N force to the left acting on it. What happens to the trolley?

    • It keeps moving at the same speed in the same direction.
    • It speeds up to the right, because the force to the right is applied to the trolley for longer.
    • It speeds up to the left, because the force to the left is the one that makes the trolley move.
    • It stops immediately, because the two forces cancel and remove all of its motion at once.

  19. Which pair of forces is balanced?

    • Two 7 N forces acting in the same direction on the same object, which add to 14 N in total
    • A 7 N force and a 14 N force acting in the same direction, which add to 21 N overall
    • Two 7 N forces acting in opposite directions on the same object
    • A 7 N force and a 14 N force acting in opposite directions, which leave a resultant of 7 N

  20. A 4 N force pushes a crate to the right and a 4 N force pulls it to the left, both along the same line. What is the resultant force?

    • 8 N to the right, which adds the two equal forces together even though they act in opposite directions
    • 4 N to the right, which keeps only the push and ignores the opposing pull acting on the crate
    • 4 N to the left, which keeps only the pull and treats it as the bigger of the two forces acting
    • 0 N

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