(1 point) A mass
weighing 4 lb4 lb stretches a spring 6 in.6 in.
The mass is displaced 8 in8 in in the downward direction from its
equilibrium position and released with no initial velocity.
Assuming that there is no damping, and that the mass is acted on by
an external force of 5cos(7t)5cos(7t) lb,
solve the initial value problem describing the motion of the
mass.
For this problem, please remember to use English units: ft, lb,
sec.ft, lb, sec....