Question

A boy of weight 40 kgf is sitting 1.2 m away from the fulcrum of a sea-saw. where should another boy of weight 60 kgf sit to keep the plank horizontal ?

Answer 1

torque balance
40×1.2=60×x
x=0.8 m

Answer 2

Hey user!

Here's the answer:

》In equilibrium when the plank is horizontal moments of force on either side of the fulcrum must be equal. Let the boy of weight 60 kgf sits 'L' distance away from the fulcrum.

》 40 kgf × 1.2 m = 60 kgf × L

》L = (40 kgf × 1.2 m) / 60

》L= 0.8 m.