A disc is rolling (without slipping) on a horizontal surface. C is its centre and Q and P are two points equidistant from C. Let vp,. and be the
magnitudes of velocities of points, P, Q and C respectively, then
If O be the point of contact of the disc with the surface , then at any instant of time the disc is rotating about point o and O is called the instantaneous centre of rotation .
Velocity of any point on the disc at a radial distance r from O is given by V = .
OQ
From fig. OQ > AC > OP
We know that