Torque from perpendicular forces at disc edge

Steps:

• Identify radius r = s/2 for the disc.
• Each force F acts tangent to the edge, so perpendicular distance (moment arm) is r for both.
• Torque from one force: τ = r F = (s/2) F.
• Total torque: 2 × (s/2) F = F s, assuming forces rotate disc same way.

Why C is correct:

• Torque formula τ = r F sinθ (θ=90°, sinθ=1) gives Fs for additive torques.

Why the others are wrong:

• A: Forces produce net torque, not cancellation.
• B: Underestimates by ignoring full additive effect (likely misread as single force).
• D: Overestimates by doubling without halving radius.

Final answer: C