Instantaneous Axis of a Cylinder rolling on a Cylinder.Let a cylinder bbb, whose axis of figure is B and angular velocity -y, roll on a fixed cylinder acm, whose axis of figure is A, either outside (as infig.
The line T on the surface bbb has for the instant no velocity it a direction perpendicular to AB; becau2e for the instant it touches, without sliding, the line T on the fixed surface aaa.
The line T on the surface bbb has also for the instant no velocity in the plane AB; for it has just ceased to move towards the fixed surface aaa, and is just about to begin to move away from that surface.
The line of contact T, therefore, on the surface of the cylinder bbb, is for the instant at rest, and is the instantaneous axis FIG.
About which the cylinder bbb turns, together with any body rigidly attached to that cylinder.