Lesson 3.04b

3.04b Rigid bodies in equilibrium Quiz: OCR Maths, Unit 19

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.04b, Rigid bodies in equilibrium: 20 multiple choice questions for the OCR Maths (H240), Unit 19: Moments, written with Revision Ninja.

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The 20 questions

  1. What is the resultant moment acting on a rigid body that is in static equilibrium?

    • Undefined
    • Infinite
    • Equal to weight
    • Zero

  2. What must the resultant moment and resultant force be for a rigid body in static equilibrium?

    • Zero
    • Maximum
    • Infinite
    • Constant

  3. At which point on a uniform rod can its weight be assumed to act?

    • At the support
    • At its quarter-point
    • At one end
    • At its midpoint

  4. Where does the line of action of weight act for a uniform rectangular lamina?

    • Bottom corner
    • Top edge
    • Longest side
    • Point of symmetry

  5. What is the direction of the reaction force exerted by a smooth vertical wall?

    • Vertically downwards
    • Parallel to wall
    • Along the ladder
    • Perpendicular to wall

  6. Which physical assumption is made when modelling a rod as being completely uniform?

    • Variable mass distribution
    • Constant mass distribution
    • Zero mass
    • Infinite stiffness

  7. What is the magnitude of the frictional force exerted by a perfectly smooth vertical wall?

    • Maximum
    • Equal to normal reaction
    • Equal to weight
    • Zero

  8. What is the standard SI unit used for the moment of a force?

    • Newtons
    • Kilograms per metre
    • Newton-metres
    • Joules per second

  9. A uniform rod of length 4 m has a mass of 6 kg. Where does its weight act?

    • 4 m from end
    • 1 m from end
    • 3 m from end
    • 2 m from end

  10. A horizontal uniform beam of weight 100 N is supported at both ends. What is each end reaction force?

    • 50 N
    • 100 N
    • 25 N
    • 200 N

  11. Where must a support be placed to balance a uniform rod with an extra weight at one end?

    • Closer to weight
    • At the opposite end
    • Exact geometric centre
    • Outside the rod length

  12. A 2 m uniform rod of weight 20 N rests on end supports. What is the weight's moment about one end?

    • 20 N m
    • 0 N m
    • 40 N m
    • 10 N m

  13. A light rod carries 10 N at 1 m and 5 N at 3 m from a pivot. What total moment acts?

    • 25 N m
    • 15 N m
    • 30 N m
    • 5 N m

  14. Which force prevents the base of a ladder from slipping on a rough floor?

    • Wall tension
    • Normal reaction
    • Floor friction
    • Ladder weight

  15. A uniform rectangular lamina measures 2 m by 4 m. How far is its centre of mass from each edge?

    • 0 m and 0 m
    • 1 m and 2 m
    • 2 m and 4 m
    • 0.5 m and 1 m

  16. When calculating unknown forces on a beam, where is it best to take moments to eliminate a reaction?

    • At the centre
    • At a support
    • At the top
    • Off the beam

  17. A non-uniform 4 m rod balances horizontally on a pivot 1 m from end A. Where is its weight acting?

    • 2 m from end A
    • 1 m from end A
    • 3 m from end A
    • 0.5 m from end A

  18. A 3 m uniform rod weighing 40 N has a 20 N load at A. What vertical force supports end B?

    • 30 N
    • 10 N
    • 20 N
    • 40 N

  19. What is the ratio of limiting friction to normal reaction force for a ladder on rough ground?

    • Ratio of lengths
    • One half
    • Zero
    • Coefficient of friction

  20. A 6 m uniform rod weighing 100 N rests symmetrically on two supports. What reaction force acts at one support?

    • 75 N
    • 25 N
    • 50 N
    • 100 N

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