Q. A uniform circular disc of mass M and radius R is suspended vertically from a horizontal axis AB fixed at a distance R/2 above the centre C of the disc. The disc can rotate freelly about the axis AB. A particle of mass m moving horizontally with velocity v strikes the point 'P' lying vertically below the centre and on the edge of the disc.Find the minimum value of v so that the disc can make full rotation about the axis AB. [Take (M/m)=3 and e=0.5].