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GCSE Questions - Forces

Q6. Adrian and Bertie are playing on a seesaw. Both children sit 2m from the pivot.

 

(a) Calculate the clockwise and anti-clockwise moments around the pivot when the seesaw is horizontal.

Bertie makes a clockwise moment.

Moment = force x perpendicular distance from the pivot point

Moment = 400 N x 2m = 800 Nm

Adrian makes an anticlockwise moment.

Moment = force x perpendicular distance from the pivot point

Moment = 500 N x 2m = 1000 Nm

[5 marks]

(b) Calculate where Adrian should sit to balance the seesawif Bertie remains 2m from the pivot.

The moment he makes must be 800 Nm to balance with Bertie and his weight is 500N, so:

800 = 500 x d

d = 800/500

d = 1.6 m

[3 marks]

(Total 8 marks)