S11. Suppose that the mass in a spring-mass-dashpot system with m = 1, c = 2, and k = 8 is set in motion (at t = 0) with x(0) = 0 and x'(0) = √7. When x(t) > 0 the spring is stretched, and the spring is compressed when x(t) < 0.
a) Find the position of the mass for all t > 0.
b) Even though the motion is not periodic, show that the mass passes through the equilibrium position every π/√7 seconds (which is half the "pseudo-period").