**EXAMPLE 5: ****Work-energy relation for a
rigid body**

The uniform bar of mass *m* and length *l* is
released from horizontal position. The spring has a face length of 2*l* and a stiffness of _{}. Calculate the angular velocity of the bar when it becomes
vertical.

**Solution:**

Force Analysis: _{} do no work and _{} are conservative

_{}

_{}

_{}

_{}

_{}

_{}

_{}

_{}