Question

A simple pendulum of length L swings in a vertical plane. The tension of the string when it makes an angle θ with the vertical and the bob of mass m moves with a speed v is (g is the gravitational acceleration

(A) mv² /L

(B) mg cosθ+ mv²/L 

(C) mg cosθ – mv² /L 

(D) mg cosθ

Answer 1

Answer is (B) mg cosθ+ mv²/L 

From the figure, 

T = mg cosθ + mg sinθ

∴ T = mg cosθ + mv² /L