A 5 kilogram (Kg) object stretches spring 0.6125 centimeters (cm) in equilibrium. If air resistance is negligible and the object is subjected to the periodic external force of Fe = 400sin(40t) Newtons or Kg•m/sec^2
a) determine the spring constant k
b) find the displacement y=y(t) assuming that the system is initially at rest in equilibrium