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J-dizzal

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## Homework Statement

The figure shows a rigid assembly of a thin hoop (of mass m = 0.25 kg and radius

*R*= 0.13 m) and a thin radial rod (of length

*L*= 2

*R*and also of mass

*m*= 0.25 kg). The assembly is upright, but we nudge it so that it rotates around a horizontal axis in the plane of the rod and hoop, through the lower end of the rod. Assuming that the energy given to the assembly in the nudge is negligible, what is the assembly's angular speed about the rotation axis when it passes through the upside-down (inverted) orientation?

## Homework Equations

ΔU=mgΔy

I=1/3 ML

^{2}(rod)[/B]

## The Attempt at a Solution

Im having trouble finding the rotational inertial of the rod and the hoop.

for the rod I am using 1/3 ML

^{2}because its I of the rod rotating about its end.

for the hoop i tried using its com and applying that to the formula I=MR

^{2}, where M=.25kg and R=.39m

Thanks

edit. complete[/B]

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