A fulcrum is placed 1.0 m from the right-hand end of a 3.0-m long wooden uniform plank of mass 40 kg. An object of mass m is placed at the extreme right-hand end to make the plank balance. What must be the mass of the object in order to balance the plank? (Ans: 20 kg)
40 kg
1.0 m
3.0 m