A simple pendulum oscillates in a verticle plane. When it passes through the mean position,the tension in the string is 3 times the weight of the pendulum bob. What is the maximum angular displacement of the pendulum of the string with respect to the vertical ?

Options

A. `30^(@)`
B. `60^(@)`
C. `45^(@)`
D. `90^(@)`

Answer

D

Explanation

At lowest pt. `T-mg=(mv^(2))/(l)impliesT=mg+(mv^(2))/(l)`
`:." "mg+(mv^(2))/(l)=3mg" "implies" "v=sqrt(2gl)`
`:.` Velocity will be zero when it is at vertical height l i.e., when the string makes an angle of `90^(@)` with vertical.
`:.` Correct choice is (d).