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I just had a question on a homework problem I was attempting, but can't find the correct solution for it yet. The answer is in the back of the book, but I wanted to know how it is derived. Anyways, here is the question:

A hollow sphere of radius .15 with I=.040 rolls without slipping up a surface inclined at 30 degrees. At a certain initial position, the sphere's total kinetic enery is 20J.

A) How much of the totak K.E. initial is rotation?

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Variables:

**Radius of sphere = .15m**

**Moment of Inertia = .040 kg * m^2**

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Attempt:

I tried this problem with setting the initial kinetic energy of the sphere-incline system to 20J. So I did:

**.5MV^2 + .5I(w)^2 = 20J**

This is the step that I get lost in. Should I try to find the mass of the system first or should I try a whole different approach? Any help would be appreciated! Thanks!