*Originally posted by wolfgang59*

**Assuming no energy loss due to friction....
**

Potential Energy gained = gMh

so initial Kinetic Energy must at least equal that

M/2 * v^2 = gMh

therefore v = sqrt(2gh)

But it seems like you are only using translational energy when considering the kinetic energy of the wheel. If the wheel is rolling, I think there should also be a rotational energy term in the expression for kinetic energy, and this term will depend on the moment of inertia. Maybe as approximation we could treat the wheel as a disk. I think that would give something like Vmin = sqrt[(4/3)gh]. If instead we treated is as either a hoop or a thin cylindrical shell, I think it would give Vmin=sqrt(gh).

EDIT: Also, I am pretty sure this type of approach is correct when considering, say, minimum speed for the wheel's getting to vertical height h going up some sort of ramp or something. But is this approach correct for considering getting over the rectangular bump mentioned here? My memory of what I learned in physics is for crap, but I am not yet convinced it is. If the bump height were R or greater, then the wheel shouldn't get over no matter how fast it is going (at least, I think I am correct in saying that -- or at least consider what would happen if h were much greater than R). Of course, he specifically stipulates in the problem that h<R, but my point is that your analysis approach doesn't suggest that there is anything interesting about when h approaches R, which really makes me question the approach. I am not sure, though.