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A mass m moves in a circle on a smooth horizontal plane with velocity v0 at a radius R0. The mass is attached to 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
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1 mv0² 4 - 2mv0²
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1 mv0² 2 - mv0²
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Correct Option: B
Applying angular momentum conservation
mV0R0 = (m)(V0)(R1/2)
∴ v¹ = 2V0
Therefore, new KE = (1/2)m (2V0)² = 2mv0²
