AIPMT | 2015Work, Power and EnergyEasy
Question
A mass m moves in a circle on a smooth horizontal plane with velocity v0 at a radius R0. 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
. The final value of the kinetic energy is :-
The tension in the string is increased gradually and finally m moves in a circle of radius
. The final value of the kinetic energy is :-Options
A.
mv02
mv02B.2mv02
C.
mv02
mv02D.mv02
Solution
Angular momentum remains Constant because of the torque of tension is zero
⇒ Li = Lf
⇒ mv0R = mv
⇒ v = 2v0
KEf =
m (2v0)2 = 2mv02
hence option (2)
⇒ Li = Lf
⇒ mv0R = mv
⇒ v = 2v0
KEf =
m (2v0)2 = 2mv02hence option (2)
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