The maximum value attained by the tension in the string of a swinging pendulum is four times the minimum value it attains. There is no slack in the string. The angular amplitude of the pendulum is

Options

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

Answer

B

Explanation

`T_(max)-mg=(mv^(2))/(R)`....(i)
From energy cons.
`ki +ui = kf +uf`
`O +mg(R-R cos)=mv^(2) +0`
`V^(2) =2gR (1- cos theta)`
Put in eq. (i)
`T_(max) = 3 mg - 2mg cos theta`
`(T_(max))/(T_(min))=4 rArr theta = 60^(@)`.