Hollow sphere rolling up a ramp

[mjolnir80]

Homework Statement

a hollow sphere is rolling long a horizontal floor at 5 m/s when it comes to a 30 degree incline. how far up the incline does it roll before reversing direction?

Homework Equations

The Attempt at a Solution

it seems like conservation of energy would work best for this problem
1/2mv^2 + 1/2I$$\omega$$^2 = mgh
im just having some problems finding $$\omega$$
am i doing this right? and if so any clues on how to find $$\omega$$?
thanks in advance

 

[Doc Al]

Assuming the sphere is rolling without slipping, ω and v are directly related. (What's the condition for rolling without slipping?) What's the rotational inertia of a hollow sphere?

Your method is fine.

 

[mjolnir80]

v=$$\omega$$r right? but we don't have the radius of the sphere
or do we....?

 

[Doc Al]

v=$$\omega$$r right?

Right.

but we don't have the radius of the sphere
or do we....?

Maybe you don't need it. (Just call it "r" and see what happens.)