Question

There are two point masses each of mass m are at the ends of a rod of mass m. The rod is released. What will be the angular speed when it becomes vertical?

• A.
• B.
• C.
• D.

Answer 1

The correct option is B

Moment of internal of the rod about refernce point (i)
$m(\frac{L}{4}{)}^2+[\frac{m{L}^2}{12}+m\left(\frac{L}{4}{)}^2\right]+m(\frac{3L}{4}{)}^2$

$=\frac{37m{L}^2}{48}$
Basing on energy conservation,
$K_i+P_i=K_f+P_f$
$0+0=\frac{l{\omega }^2}{2}+P_f$