- #1
Victorian91
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Homework Statement
A uniform rod AB is hinged smoothly at A. The length L of the rod is 50cm. Determine
a) The angular velocity,
of the rod when it makes an angle (Theta) =30o with the verticle.
( Moment of inertia of rod about axis through one end and perpendicular to the rod = 1/3 mL2 ; g =9.8m s-2
Homework Equations
Ki + Ui = Kf + Uf
The Attempt at a Solution
0 + mghi = 1/2 Iw2 + mghf
Where hi = 1/2 L
and hf = 1/2 L ( 1-cos Theta )
Then plugging in the information given,
Angular velocity = 7.1 rad s-1
When the rod is vertical, let the horizontal line which passes through the center of the rod be the reference line where h=0 and U=0.
Can anybody tell me why the final potential energy is not just 1/2 L cos Theta.
Or is it 1/2 L ( 1-cos Theta ) ?
Thanks...