A solid disk is rolling without slipping on a level surface at a constant speed of 2.50

Question:

A solid disk is rolling without slipping on a level surface at a constant speed of 2.50 m/s.
(a) If the disk rolls up a 30.0" ramp, how far along the ramp will it move before it stops?
(b) Explain why your answer in part (a) does not depend on either the mass or the radius of the disk.