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GCSE Questions: Moments and Centre of Gravity

Q6. The diagram shows a fork-lift truck lifting a heavy crate.

(a) The crate weighs 11 500 N and is lifted vertically 2.60 m.

Calculate the work done to lift the crate.

Work done = force x distance moved along the line of action of the force

W = Fs

W = 11 500 x 2.60

W = 29 900 J

[3 marks]

(b) The weight of the crate causes a clockwise moment of 13 800 Nm about the centre of the front wheel of the fork-lift truck.

The weight of the fork-lift truck and driver cause an anticlockwise moment.

What is the minimum size of the anticlockwise moment needed so that the fork-lift truck does not topple over?

So it does not topple the moment must be at least equal to the moment of the crate = 13 800 Nm

[1 mark]

(c)

(i) Write down the equation which links distance, force and moment of a force.

moment = force x perpendicular distance from the fulcrum (turning point)

[1 mark]

(ii) Calculate the distance 'd' marked on the diagram.

M = Fd

13,800 = 11,500 x d

d = 13,800/11,500

d = 1.20 m

[3 marks]

[8 Marks TOTAL]