Rolling Motion homework?

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Homework Statement



An 8 cm, 400 g sphere is released from rest at the top of a 2.1 m long, 25 degrees incline. It rolls, without slipping, to the bottom.
a. What is the sphere's angular velocity at the bottom of the incline?
b. What fraction of its kinetic energy is rotational?

Homework Equations



K rolling = (1/2) (I cm) (w^2) + (1/2) (M) (v cm^2)

The Attempt at a Solution



I know that the I cm for a sphere is 2/5 M R^2. I need to solve this equation for angular velocity but I can't seem to get the velocity of the centre of mass. I tried finding the potential energy and saying it all got converted to kinetic to find it but itgave me the wrong answer.

I found a, I just needed to substitute V cm = Rw to get the equation with only one unknown.
I'm still not sure about b though
Scratch that, got it. Thanks for your help
 
Last edited:

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