A particle of mass 100 g is suspended from the end of a weightless string of length 100 cm and is rotated in a vertical plane. The speed of the particle is `200 cm*s^(-1)` when the string makes an angle of `theta =60^@` with the verctcal. Determine
(i) the tension in the string when `theta =60^@` and

Explanation

The body is rotated in a vertical plane [Fig.1.34].

At point B, when the string makes an angles `60^@` with the vertical , the velocity of the particle is v(say).
If the tension in the string is T , then
`T-mg cos 60^@=(mv^2)/r`
`therefore T=mg cos 60^@+(mv^2)/r`
Here, `v=200 cm *s^(-1), r=100 ,m=100g`
`therefore T=100xx980xx1/2 +(100xx(200)^2)/(100) =8.9xx10^4 dyn`.