In the case of a circular arc cam with a flat-faced reciprocating follower, when the follower is in contact with nose of cam, the external spring force required for maintaining the contact between follower and cam is:
(a) Greater than the force due to gravity of mass of the follower
(b) Greater than the inertia force of the follower
(c) Smaller than the inertia force of the follower
(d) Greater than the weight of the follower