Three children are trying to balance on a seesaw, which consists of a fulcrum rock, acting as a pivot at the center, and a very light board 3.6 m long. Two playmates are already on either end. Boy A has a mass of 40 kg, and girl B a mass of 30 kg. Where should girl C, whose mass is 20 kg, place herself so as to balance the seesaw?

the girl C should sit on the right side at 0.9 m from the fulcrum.

Explanation:

Given:

Length of the board, L = 3.6 m

Mass of boy, A = 40 kg

Mass of girl B = 30 kg

Mass of girl C, = 20 kg

now,

assume that Girl C is on the right side of the seesaw

let, x be the distance of the GIrl C from the fulcrum.

since, the system is in equilibrium, thus Equating the torque on the both sides

therefore,

40 * 1.8 = 20 * (x) + 30 * 1.8

72 = 20x + 54

or

20x = 18

or

x = 0.9 m

hence, the girl C should sit on the right side at 0.9 m from the fulcrum.