JEE Advanced Model Paper 19 with solutions for online practice

In the figure shown a plank of mass m is lying at rest on a smoothhorizontal surface. A disc of same mass m and radius r is rotated to anangular speed ω0 and then gently placed on the plank. It is found thatfinally slipping cease, and 50% of total kinetic energy of the disc andplank system is lost. Assume that plank is long enough. µ is coefficientof friction between disc and plank.