A brick of mass 4 kg hangs from the end of a spring. When the brick is at rest, the spring is stretched by 7 cm. The spring is then stretched an additional 2 cm and released. Assume there is no air resistance. Note that the acceleration due to gravity, g = 980 cm/s^2.
Set up a differential equation with initial conditions describing the motion and solve it for the displacement s(t) of the mass from its equilibrium position (with the spring stretched7 cm).