Question -
Answer -
750N and 250 N in the respective cases; Method (b)
Mass of the block, m = 25kg
Mass of the man, M = 50 kg
Acceleration due to gravity, g = 10 m/s2
Force applied on the block, F =25 × 10 = 250 N
Weight of the man, W = 50 ×10 = 500 N
Case (a): When the man lifts the blockdirectly
Inthis case, the man applies a force in the upward direction. This increases hisapparent weight.
∴Action on the floor by the man = 250 + 500 =750 N
Case (b): When the man lifts the block usinga pulley
Inthis case, the man applies a force in the downward direction. This decreaseshis apparent weight.
∴Action on the floor by the man = 500 – 250 =250 N
Ifthe floor can yield to a normal force of 700 N, then the man should adopt thesecond method to easily lift the block by applying lesser force.