Question

A simple pendulum of length L and bob of mass M is oscillating in a vertical plane about a vertical line within angular limit -θ₀ to θ₀ . For an angular displacement θ(|θ|<θ₀); the tension in the string is T and the velocity of bob is v. Which of the following statements is incorrect?

(1) T = Mg cosθ , at θ 

(2) a_net = θ₀

(3) T = Mg cosθ , at θ = θ₀

(4) a_net = g

Answer 1

The motion of a pendulum bob in circular motion with radius ‘L’. The forces are resolved along the string (radius) and ⟂ radius. Net force along radius should be Mv²/R.

(∵ the tension also acts in addition to weight)