# Hollow sphere rolling up a ramp

1. Feb 4, 2009

### mjolnir80

1. The problem statement, all variables and given/known data
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?

2. Relevant equations

3. 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 $$\omega$$?

2. Feb 4, 2009

### Staff: Mentor

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.

3. Feb 4, 2009

### mjolnir80

v=$$\omega$$r right? but we dont have the radius of the sphere
or do we.................?

4. Feb 4, 2009

### Staff: Mentor

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