How Much Sooner Does a Box Reach the Bottom of an Incline Compared to a Disk?

[ronho1234]

A disk and a box of equal mass are released from the top of two inclines both of which are a height h above the ground and make an angle θ to the horizontal. Let the radius of the disk be R. How much sooner does the box reach the bottom of the incline than the disk?
Express your answer in terms of some or all of the variables m, h, theta, and R, as well as the acceleration due to gravity g.

 

[Mindscrape]

Probably best to tackle this one with conservation of energy and with moments of inertia :)

 

[rcgldr]

The problem statement doesn't mention a cofficient of friction. Is the inclined plane frictionless for the box and not frictionless for the disk?