. Homework Statement
I want to know why the answer is C not B. Thanks.
1. the force will be -kx , as spring opposes the displacement
draw the force diagram on the block and see what is the net force on the block-ask yourself can it support oscillations of the block or not ?
but you should give complete argument;
1. initially a displacement say y in the vertical direction will lead to two forces- compression of upper spring will give -ky down ward and extension of lower one will give -ky down ward, as there is significant friction F(friction) will oppose the motion of the mass -pointing up if movement is downward-
after reaching the rest position the energy of the mass will move further down and spring forces will point up but the friction will oppose the motion . so a cycle of oscillation can not be sustained mainly due to energy dissipation .