A mass m moves in a circle on a smooth horizontal plane with velocity v 0 at a radius R 0 . The mass is attached to a string which passes through a smooth hole in the plane as shown.
The tension in the string is increased gradually and finally m moves in a circle of radius R0/2 . The final value of the kinetic energy is :-
Answer & explanation
Correct answer: option 2
Angular momentum remains Constant because of the torque of tension is zero.
Li = Lf
mvoR = mv\(\frac{R}{2}\)
⇒ v = 2vo
KE = \(\frac{1}{2}mv^2\)
= \(2 mv_o^2\)