Two discs of same moment of inertia rotating about their regular axis passing through centre and perpendicular to the plane of disc with angular velocities 00 and . They are brought into contact face to face coinciding the axis of rotation. The expression for loss of energy during this process is:- (a)-1(w - w) (b) I(W - W) (c)(W-W) (d) / 1 (w + w)