Answer:
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.