Moment of force equals tension times perpendicular distance from Q to line of action at P

Steps:

• Identify the line of action of tension F, which acts along the thread from P.
• Determine the perpendicular distance from Q to this line of action.
• In the diagram, this distance is labeled y.
• Compute moment as F multiplied by y.

Why C is correct:

• By definition, moment = force × perpendicular distance; y is that distance, so moment = Fy.

Why the others are wrong:

• A: w is not the perpendicular distance to the line of action.
• B: x is a parallel or irrelevant component, not the moment arm.
• D: z is an out-of-plane distance, irrelevant for 2D lamina rotation.

Final answer: C