Homework Statement
A box of mass M is suspended by a spring of stiffness k. A small block of mass m is placed inside the box. If the system is pulled downward by a distance d and then released from rest:
a.) find the force between the bottom of the box and the block as a function of time...
I'm confused about how to find acceleration. I understand that it is needed to determine the force of reaction by F(m+M)=mg+ma. Can anyone explain it? I've got the x(t)=dcos(ωt) and ω=√(k/(m+M)). Where do I go from there? Do I just find the second derivative of x(t)? And then -ω2dcos(ωt) is...