System of Particles and Rotational Motion

A heavy iron bar of weight 12 kg is having its one end on the ground and the other on the shoulder of a man. The rod makes an angle 60 with the horizontal, the weight experienced by the man is :

1. 3 kg
2. 6 kg
3. 6 3 kg
4. 12 kg

Answer

(1) 3 kg

Solution

[figure]

Smooth shoulder its reaction N is perpendicular to the rod.

Torque about O =0: W L2 60 =N L

N= W2 60 = W4

= 124=3 kg wt

Answer: (1)