Q.

A pendulum of length ℓ=1 m having a bob of mass m=1 kg is hanging from a rigid support. If the bob is projected horizontally with a velocity v0=35 m/s. The tension in the string is 6k Newton when angle made by the string is 60° from vertical as shown. Find the value of k.


Ans.

(5)

12mv02=12mv2+mgl(1-cosθ),    T-mgcosθ=mv2R