The thin uniform rod in the figure below has length 9.0 m and can pivot about a horizontal, frictionless pin through one end. It is released from rest at angle θ = 39° above the horizontal. Use the principle of conservation of energy to determine the angular speed of the rod as it passes through the horizontal position.

Question

ac3 · Answer

attachment

ac3 · Answer

Someone tell me why i'm wrong. Here is my work.

ac3 · Answer

I see that rod spin almost like a disk so I=(mr^2)/2

ac3 · Answer

|dw:1448070944084:dw|