A uniform rod `AB` of mass `m` length `2a` is allowed to fall under gravity with `AB` in horizontal. When the speed of the rod is `v` suddenly the end `A` is fixed. Find the angular velocity with which it begins to rotate.

Options

A. `v/(2a)`
B. `(4v)/(3a)`
C. ` v/(3a)`
D. `(3v)/(4a)`

Answer

D

Explanation

Angular mometum about `A` will, be conserve i.e.
`L_(i)=L_(f)`
or ` mva=Iomega`
or `mva=(m(2a)^(2))/3 omega:. omega=(3v)/(4a)`