Physics.

[Nate]

ok I could name this, "What is the rotational velocity of a perfect sphere travelling down a ramp in a frictionless world?".  You would click on that? I think not...

[Sidoh]

ok I could name this, "What is the rotational velocity of a perfect sphere travelling down a ramp in a frictionless world?".  You would click on that? I think not...

Then the riddle would be entirely too easy.  All you'd have to say is 0 and you'd be correct; no math involved!  Booorrrinngg... :(

You could name it "Ramp + Sphere - Friction = ?" or something like that.  You just have to be creative. :)

[iago]

or just "Physics: rolling ball"