What are the curves of contact on a convex body $B$ rolling down an inclined plane?Assume $B$ is smooth, and there is sufficient friction to prevent slippage.
Certainly, one can develop a geodesic to a straight line on a plane by rolling $B$ so that the geodesicis the point of contact, but it doesn't appear that this in general would be the point of contactin the physical situation of free rolling under gravity. It is for a sphere, which will roll alonggreat circles. And an ellipsoid should roll along its three simple closed geodesics (although thereare significant instabilities with all but the shortest closed geodesic—I'd prefer to ignorestability issues). But for other shapes,I imagine that an off-center center of gravity (and perhaps rotational momentum?) will cause the rolling to deviate from ageodesic. (But I am uncertain of this. Please correct me if I'm wrong!)
Assuming this is correct (that rolling curves are not always geodesics),what are the conditions that determine if a curve $\gamma$ is a rolling curve:$\gamma$ is the trace of the point of contact between $B$ and an inclined plane as it rolls,from some initial position?Perhaps: If $p \in \gamma$ is a point of contact, then (a) the normal vector $N$ of $\gamma$ at $p$ must beperpendicular to the plane, and (b) the center of gravity of $B$must lie in the osculating plane of $\gamma$ at $p$ (the plane containing $N$ andthe tangent $T$ vector at $p$)?
Have what I christened rolling curves been studied in the literature? If so, under what name?My searches have been unsuccessful. Can you think of shapes outside of {sphere, ellipsoid, cylinder} where the rolling curves can be determined? Thanks for any thoughts or pointers!