Disc of mass m, is placed on a table. a stiff spring is attached to it and is vertical. the other end of the spring is attached to a disc of mass m,. (fig.). wh

Disc of mass m, is placed on a table. A stiff spring is attached to it and is vertical. The other end of the spring is attached to a disc of mass m,. (Fig.). What minimum force should be applieg to the upper disc to press the spring such that the lower disc is lifted off the table when the external force is suddenly removed ? F m, m2 (A) F m,g (B) F m.g min min m +m. a m.m2 (C) F (m, + m.)g (D) F min min