Question

When a boy weighing 30kgf sits at one end of a 4m long see saw,it gets depressed at this end. How can it be brought to the horizontal position by a man weighing 40kgf​

Answer 1

Answer

By sitting at distance 1m from the centre on the side opposite to the boy

Explaination

This boy has a perpendicular distance of 2 m from the centre from the point of application of force 20 Kgf. Hence moment of force is 20×2=40Kgf. This must be balanced  by horizontal by a man of having perpendicular distance from the centre on the side opposite to the boy is x with a weight of 40Kgf. Hence moment of force is 40×x=40. Hence x=1m.

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