Question

A girl weighing 40kgf sits at one end of am long see saw.To make it horizontal, at what distance a girl weighing 60kgf must sit?​

Answer 1

Answer:

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

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.