JEE Main 2024 Physics question
A stone of mass 900 g is tied to a string and moved in a vertical circle of radius 1 m making 10 rpm. The tension in the string, when the stone is at the lowest point is (if π² = 9.8 and g = 9.8 m/s²)
Answer: (A)
Solution
ω = 10 rpm = 10 × (π/30) = π/3 rad/s. At the lowest point T − mg = mω²r, so T = 0.9 × 9.8 + 0.9 × (π²/9) × 1 = 0.9 × 9.8 (1 + 1/9) = 9.8 N.