Lesson 4C.3.2

4C.3.2 Equilibrium of rigid bodies Quiz: Pearson Edexcel Further Maths, Unit 32

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 4C.3.2, Equilibrium of rigid bodies: 20 multiple choice questions for the Pearson Edexcel Further Maths (9FM0), Unit 32: Centres of mass and equilibrium of rigid bodies, written with Revision Ninja.

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The 20 questions

  1. Three non-parallel coplanar forces are in equilibrium on a rigid body. What must be true of their lines of action?

    • They meet at a single point
    • They must have equal magnitudes
    • They are all parallel
    • Their magnitudes sum to zero

  2. A rigid body is suspended freely from a fixed point. In equilibrium, where is its centre of mass?

    • directly at the point of suspension
    • vertically below the point of suspension
    • horizontally from the point of suspension
    • vertically above the point of suspension

  3. For a rigid body in equilibrium under coplanar forces, what are the resultant force and resultant moment?

    • both zero
    • zero force but non-zero moment
    • both equal
    • non-zero but equal

  4. A uniform rod has one end on a smooth horizontal floor and the other end against a smooth vertical wall. Which force acts at the wall end?

    • the normal reaction from the wall, horizontal
    • friction along the floor
    • a vertical reaction from the wall
    • the weight of the rod

  5. For a body in limiting equilibrium on a rough plane, the friction force F and normal reaction R satisfy which condition?

    • F = R/mu
    • F >= mu R
    • F <= mu R
    • F = mu R always

  6. A rigid body rests on a horizontal plane with no other vertical forces acting. What is its normal reaction?

    • twice its weight
    • its weight
    • its mass
    • zero

  7. Why is taking moments about the point where an unknown reaction acts often useful?

    • the unknown force becomes larger
    • the body is then treated as a particle
    • that reaction has zero moment about the point, so it drops out of the equation
    • the weight then has zero moment

  8. A uniform ladder of length 10 m and weight 40 N leans against a smooth vertical wall at 45 degrees to a rough horizontal floor. What is the normal reaction from the wall?

    • 10 N
    • 20 N
    • 40 N
    • 80 N

  9. A uniform beam AB of length 6 m and weight 60 N rests horizontally on supports at A and B. A 30 N load acts at 2 m from A. What is the reaction at A?

    • 60 N
    • 40 N
    • 30 N
    • 50 N

  10. A block of weight 40 N rests on a rough horizontal floor. What is the least coefficient of friction for it to stay at rest when a horizontal force of 10 N is applied?

    • 4
    • 0.4
    • 10
    • 0.25

  11. Forces of 3 N and 4 N act at right angles at a point of a body in equilibrium under three forces. What is the magnitude of the third force?

    • 7 N
    • 1 N
    • 12 N
    • 5 N

  12. A 4 kg block rests in equilibrium on a smooth plane inclined at 30 degrees, held by a string parallel to the slope (g = 10 m/s^2). What is the tension?

    • 20 N
    • 34.6 N
    • 10 N
    • 40 N

  13. Two forces of 6 N each act at a point with an angle of 120 degrees between them. What is their resultant?

    • 6sqrt(3) N
    • 12 N
    • 6 N
    • 0 N

  14. A uniform rod AB of length 2 m and weight 20 N is hinged at A and inclined at 60 degrees to the horizontal, with end B held by a vertical string. What is the tension in the string?

    • 5 N
    • 20 N
    • 40 N
    • 10 N

  15. A 5 kg block rests on a rough horizontal floor with coefficient of friction 0.4 (g = 10 m/s^2). What is the minimum horizontal force needed to start it moving?

    • 2 N
    • 20 N
    • 50 N
    • 12.5 N

  16. A uniform ladder of length 10 m and weight 40 N rests with its top on a smooth vertical wall and its foot on a rough horizontal floor, inclined at 60 degrees to the floor. What is the least coefficient of friction at the floor for equilibrium?

    • 1/2
    • sqrt(3)/2
    • 1/4
    • 1/(2 sqrt3), about 0.289

  17. A block of weight 20 N rests on a smooth plane inclined at 30 degrees and is held in equilibrium by a horizontal force P. What is P?

    • 10 N
    • 20 N
    • 20sqrt(3) N
    • 20/sqrt(3) N

  18. A uniform beam AB of weight 24 N and length 4 m rests horizontally on supports at its ends. A 12 N weight is placed 1 m from A. What is the reaction at A?

    • 21 N
    • 24 N
    • 15 N
    • 18 N

  19. Why must three non-parallel coplanar forces in equilibrium on a rigid body have concurrent lines of action?

    • Because their magnitudes must all be equal
    • Taking moments about the point where two lines of action meet, the third force has zero moment, so its line passes through that point
    • Because friction must then be zero
    • Because the weight always acts through the centre of mass

  20. A uniform beam AB of length 8 m and weight 80 N rests on supports at A and B. A 40 N load acts at 2 m from A. What is the reaction at B?

    • 60 N
    • 40 N
    • 70 N
    • 50 N

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