In the above question, `ifu=sqrt(gR)` then
(a) after rotating an angle `theta` , velocity of the bob becomes zero. Find the value of `theta` .
(b) If mass of the bob is `'m'` then what is the tension in the string when velocity becomes zero?

Answer

B

Explanation

(a) Velocity becomes zero at height `h_(2)` discussed in article `10.5` where, `h_(2)=(u^(2))/(2g)=(gR)/(2g)=(R)/(2)`
Now, `h_(2)=R(1-costheta)`
:. `(R)/(2)=R(1-costheta) impliestheta=60^(@)`
(b) `T=mgcostheta=(mg)/(2)attheta=60^(@)`