Torque Balance on a Pivoted Beam

Steps:

• Calculate clockwise torques: e.g., 6N weight at 1m gives 6Nm, another force contributes to total clockwise torque.
• Calculate anticlockwise torques from weights: their net provides the imbalance to counter.
• For equilibrium, torque from F equals net torque from weights: F × distance = net torque.
• Solve for F using given positions, yielding 12N to balance.

Why B is correct:

• By the principle of moments, ∑(force × perpendicular distance) = 0 about pivot, so F balances the unequal weight torques exactly at 12N.

Why the others are wrong:

• A: 6N ignores torque arms, underestimating the balancing force needed.
• C: 3N confuses force magnitude with half a single weight, not torque equilibrium.
• D: 60N overestimates by treating distances as additive rather than lever arms.

Final answer: B