A massless rod S having length 21 has equal point masses attached to its two ends as shown in figure. The rod is rotating about an axis passing through its centre and making angle α with the axis. The magnitude of change of momentum of rod i.e. \(\rm \left|\frac{dL}{dt}\right|\) equals
1
2 m I3ω2sin θ. cos θ
2
mI2ω2sin 2θ
3
mI2sin 2θ
4
m1/2I1/2ω sin θ.cos θ