A particle performs uniform circular motion with an angular momentum L. If the angular frequency f of the particle is doubled, and kinetic energy is halved, its angular momentum becomes

A.

4L

B.

2L

C.

L2

D.

L4

As we know that, angular momentum, l=mvr
 L=mv(vω) [v=rω]
 L=mv2ω   L=2ω(12mv2)
 L=2ω(K.E)      L K.Eω
L2L1=KE2(KE1)ω1ω2=(KE12KE1)(ω12ω1)
L2=L14