Lesson 3.03k

3.03k Equilibrium of particles: Equilibrium of particles (3.03k) Quiz: OCR Maths, Unit 18

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.03k, Equilibrium of particles: Equilibrium of particles (3.03k): 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. What assumption is made about the contact force for a smooth surface?

    • Variable friction
    • Maximum friction
    • No friction
    • Constant friction

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

    • Zero
    • One
    • Maximum
    • Equal to mass

  3. In mechanics, what does modelling a string as 'light' imply about its mass?

    • Mass is constant
    • Mass increases
    • Mass is zero
    • Mass is infinite

  4. What property remains constant throughout an inextensible string under tension?

    • Acceleration of particles
    • Frictional force
    • Mass of particles
    • Reaction force

  5. What is assumed about tension on either side of a smooth fixed pulley?

    • It is halved
    • It is zero
    • It is equal
    • It is doubled

  6. According to Newton's Third Law, contact forces between two touching particles are always what?

    • Equal and parallel
    • Perpendicular
    • Equal and opposite
    • Unequal and opposite

  7. When resolving weight down a plane inclined at angle θ, which expression is used?

    • mg tan(θ)
    • mg sin(θ)
    • mg sec(θ)
    • mg cos(θ)

  8. Which component of weight acts perpendicular into a plane inclined at angle θ?

    • mg tan(θ)
    • mg sin(θ)
    • mg cos(θ)
    • mg cosec(θ)

  9. A force of 10 N acts at 60° above the horizontal. What is its horizontal component?

    • 8.66 N
    • 5 N
    • 0 N
    • 10 N

  10. A force of 20 N acts at 30° above the horizontal. What is its vertical component?

    • 20 N
    • 5 N
    • 10 N
    • 17.3 N

  11. A particle of mass 4 kg rests on a smooth 30° slope. What is the normal reaction?

    • 33.9 N
    • 39.2 N
    • 9.8 N
    • 19.6 N

  12. Three coplanar forces in equilibrium can be arranged to form which closed geometric shape?

    • Line of forces
    • Square of forces
    • Triangle of forces
    • Circle of forces

  13. A particle experiences horizontal forces of 12 N right and F N left in equilibrium. What is F?

    • 6 N
    • 24 N
    • 12 N
    • 0 N

  14. A 3 kg mass hangs in equilibrium attached to a light string. What is the string tension?

    • 9.8 N
    • 29.4 N
    • 0 N
    • 3 N

  15. Forces (2i + 3j) N and (-2i + k j) N keep a particle in equilibrium. What is k?

    • 0
    • 3
    • 2
    • -3

  16. A force has horizontal component 3 N and vertical component 3 N. What is its angle above horizontal?

    • 60°
    • 90°
    • 30°
    • 45°

  17. Forces (a i + 4 j), (2 i - b j), and (-5 i + j) balance. What are a and b?

    • a = 5, b = 3
    • a = -3, b = -5
    • a = 3, b = 5
    • a = 3, b = -5

  18. What horizontal force P holds mass m in equilibrium on a smooth slope inclined at angle θ?

    • mg cot(θ)
    • mg sin(θ)
    • mg cos(θ)
    • mg tan(θ)

  19. What is the state of a system of two equal masses connected over a smooth peg on identical smooth slopes?

    • Accelerating down
    • Accelerating up
    • Moving in circles
    • In equilibrium

  20. For three forces in equilibrium, Lami's theorem relates each force magnitude to the sine of what?

    • Right angle
    • Adjacent angle
    • Inclined angle
    • Opposite angle

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