Vertical force equilibrium in statics

Steps:

• Calculate weight: mg = 85 kg × 9.8 m/s² = 833 N.
• Each wire tension T contributes vertical component T sin(20°); total vertical support = 2T sin(20°).
• At equilibrium, 2T sin(20°) = 833 N.
• Solve: sin(20°) ≈ 0.342, so T = 833 / (2 × 0.342) ≈ 1218 N = 1.2 kN.

Why C is correct:

• Matches Newton's first law for vertical equilibrium: sum of vertical tension components equals weight.

Why the others are wrong:

• A: Underestimates by using cos(20°) instead of sin(20°).
• B: Equals weight divided by 2, ignoring angle.
• D: Doubles the correct tension, possibly from horizontal components.

Final answer: C