Principle of Moments in Rotational Equilibrium

Steps:

• Recall that rotational equilibrium occurs when net torque is zero, meaning clockwise moments equal anticlockwise moments.
• Identify that the statement specifies clockwise moments about "any point," requiring anticlockwise moments about the same reference for balance.
• Evaluate choices: The completion must ensure moments are calculated consistently about one point.
• Select D, as it maintains the principle's requirement for identical reference points.

Why D is correct:

• The principle of moments states that for equilibrium, ∑ clockwise moments = ∑ anticlockwise moments about the same point, ensuring net torque is zero.

Why the others are wrong:

• A: Implies different points, violating the need for consistent reference in torque calculations.
• B: Centre of gravity is irrelevant; the principle applies about any point, not specifically the CoG.
• C: Pivot is a specific case, but the principle holds generally about any chosen point.

Final answer: D