A uniform seesaw, 5m long, is supported at its centre. A boy weighing 40 kgf sits at a distance of 1 m from the centre of the seesaw. (i) To which class of lever does it belong ? (ii) Find where a girl of weight 20 kgf must sit on the seesaw so as the balance the weight of the boy.

A uniform seesaw, 5m long, is supported at its centre. A boy weighing

1.	A uniform seesaw, 5m long, is supported at its centre. A boy weighing 40 kgf sits at a distance of 1 m from the centre of the seesaw. (i) To which class of lever does it belong ? (ii) Find where a girl of weight 20 kgf must sit on the seesaw so as the balance the weight of the boy.
Answer» SOLUTION :(i) The seesaw has the fulcrum F at its centre i.e., between the load and the effort. It is a class I lever. (Ii) To BALANCE the weight of the boy, LET the girl be sitting at a distance x METRE from the centre on the opposite side of the boy, then Effort arm=x metre, load arm=1 metre, Taking MOMENTS about F, `40xx1=20xx x` `therefore x=(40)/(20)=2m.` Hence the girl must sit at a distance 2 m from the centre on the opposite side of the boy.