Length of a simple pendulum is 2 m and mass of its bob is 0.2 kg .If the tension in the string exceeds 4 N, it will break. If `g=10 m//s^(2)` and the bobis whirled in a horizontal plane , the maximum angle through which the sting can make with vertical during rotation is

Options

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

Answer

C

Explanation

`L=2m ,m=0.2 kg,T=4N`
`T=mg(3-2 cos theta)`
`4=0.2xx10[3-2 cos theta ]`
`2=3-2 cos theta`
`2-3=-2 cos theta`
`+(1)/(2)=cos theta `
`theta = cos ((1)/(2))=60^(@)`