Aforce of 4 pounds stretches a spring 1 foot. a mass weighing 3.2 pounds is attached to the spring, and the system is then immersed in a medium that offers a damping force numerically equal to 0.4 times the instantaneous velocity. (use g-32 ft/s2 for the acceleration due to gravity.) (a) find the equation of motion if the mass is initially released from rest from a point 1 foot above the equilibrium position. x(t) (b) express the equation of motion in the form x(t) = ae-at sin( v/ ? 2-12 t + e). (round ? to two decimal places.) x(c) (c) find the first time at which the mass passes through the equilibrium position heading upward