In Landau's Mechanics volume at section 32 solved problem no. 5, the instantaneous axis is chosen as the one which coincides with the line where the cylinder touches the plane. This is possible only if there is rolling without slipping. My question is, had it been rolling with forward slipping, the instantaneous axis should be somewhere placed outside the cylinder. Am I right?
PROBLEM 5. Find the kinetic energy of a cylinder of radius $\:R\:$ rolling on a plane, if the mass of the cylinder is so distributed that one of the principal axes of inertia is parallel to the axis of the cylinder and at a distance $\:a\:$ from it, and the moment of inertia about that principal axis is $\:I$.