A constant external torque `tau` acts for a very brief period `/_\t` on a rotating system having moment of inertia `I` then

Options

A. the angular velocity of the system will change by `tau/_\t//I`
B. the angular velocity of the system will change by `tau/_\t//I`
C. if the system was initially at rest, it will acquire rotational kinetic enegy `(tau/_\t)^(2)//2I`
D. the kinetic energy of the system will change by `(tau/_\t)^(2)//(2I)`

Answer

A, B, C, D

Explanation

Let `L=`angular momentum
`tau=(dL)/(dt)` or `dL=taudt`
For constant torque `/_\L=tau/_\t=I/_\omega`
or `Iomega` (if `omega_(I)=0)`
Rotational kinetic energy `=Iomega^(2)//2=(/_\L)^(2)//2l`