Question

A plank of length l and mass m is standing vertically on a

frictionless surface. The plank starts to fall at t = 0. Assuming conservation of energy,

(a) calculate the angular velocity of the plank when it makes an angle θ from the

surface.

(b) Calculate the angular velocity just before the center of mass hits the floor (rod

becomes completely horizontal).

Answer 1

Answer a)
$w \: = \sqrt{ \frac{12g}{l} \frac{(1 - \sin(a) }{(3 { (\cos(a) ) }^{2} + 1)} }$


b)
$w = \sqrt{ \frac{3g}{l} }$
Hope, you understand my answer and it may helps you!!

Answer 2

plz refer to the attachment for answer

thanks