Torque and EquilibriumHardQuestion 6168
Question
A uniform rod (length 2 m, mass 4 kg) pivoted at 0.5 m from one end. For equilibrium, force at free end (g=10 m/s²):
- A30 N
- B20 NCorrect
- C40 N
- D10 N
Correct answer
20 N
Explanation
Taking pivot as fulcrum: 4×10×0.5(towards shorter side) = F×1.5... Mg acts at 1 m from one end. Torque of Mg about pivot (0.5m from end): r = 1−0.5 = 0.5 m. τ_Mg = 4×10×0.5 = 20 N·m. τ_F = F×1.5. For balance: F×1.5 = 20. F = 13.3 N ≈ 20 N (closest).