Question

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 \(60^\circ\) with the horizontal, the weight experienced by the man is :

• A. 6 kg
• B. 12 kg
• C. 3 kg
• D. \(6\sqrt{3}\) kg

Answer 1

The Correct Option is C

Given:

- Weight of the bar \( W = 12 \, \text{kg} \),
- The bar makes an angle \( \theta = 60^\circ \) with the horizontal,
- Let \( N_1 \) be the normal force at the ground and \( N_2 \) be the force experienced by the man’s shoulder.

Condition for equilibrium about the pivot:

Torque about \( O = 0 \).

Taking moments about \( O \):

\(120 \left(\frac{L}{2} \cos 60^\circ \right) - N_2 L = 0\)

Simplifying:

\(N_2 = \frac{120}{2} \cdot \frac{1}{2} = 30 \, \text{N}.\)

Converting to weight experienced:

\(\text{Weight} = \frac{30 \, \text{N}}{10 \, \text{m/s}^2} = 3 \, \text{kg}.\)

The Correct answer is: 3 kg