Algodoo

Question:
if you 2 circles:
- a small circle with radius r
- a big one with radius R
let's say R = 3r
if we roll the small circle on the big circle, how many turns/revolutions does the small circle need in order to move all around the big one?

think about it, then take a look at the experiments below!
inspired from "https://youtu.be/kN3AOMrnEUs" by MindYourDecisions


CONCLUSION:
the number of revolutions of a circle isn't equivalent to the distance it's perimiter crosses,
it has something to do with the shape of the surface it's crossing !