Angular velocity of suspended rod

[Prathamesh]

Homework Statement

A uniform rod of length L & mass m is suspended through an end. It is shifted through an angle of π/2 radian i.e. made horizontal and then released. Find angular velocity when rod is vertical.[/B]

Homework Equations

The Attempt at a Solution

My attempt to a problem is attached
with this post.

But
Solution says
By energy conservation law
1/2 I ω²= mg L/2
(ω = angular velocity)
Hence
ω=√ (3g/L)

Which one is correct? N why other is wrong?[/B]

 

[Saksham Dhull]

but in your soln you have assumed that torque remains constant throughout which is wrong
You must correct it and integerate to get the right answer

 

[Prathamesh]

Nope...i ve found the torque acting on the rod when it is in hzt position only... and hence angular acceleration (alpha) also changes with theta...so by putting theta =π/2 i ve found w