This problem is an example of critically damped harmonic motion. A mass m = 3 kg is attached to both a spring with spring constant k = 243 N/m and a dash-pot with damping constant c = 54 N⋅s/m. The ball is started in motion with initial position x0 = 2 m and initial velocity v0 = −21 m/s. Determine the position function x(t) in meters. x(t) =