Question

In the diagram shown, how far from the fulcrum should the 150kg person sit to keep the seesaw balanced if the 50kg person is 3m away from the pivot?

Answer 1

1.6m

Torque 0f 40kg weight must be equal and opposite totorque of 30kg weight

Torque =force×arm length

40kg×g×1.2m=30kg×g×x

X=1.6m

Load x Load arm = Effort x Effort arm

Here, take the 50 kg boy as the load and the 40 kg boy as the effort.

50 x 1.2 = 40 x effort arm

60 = 40 x effort arm

Effort arm = 1.5 m

So if the 50 kg boy sits 1.2 m from the fulcrum of a see-saw then the other boy of 40 kg should sit on the other side at a distance of 1.5 m from the fulcrum.