Aforce of 5 pounds stretches a spring 1 foot. a mass weighing 6.4 pounds is attached to the spring, and the system is then immersed in a medium that offers a damping force numerically equal to 1.2 times the instantaneous velocity. (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) = correct: your answer is correct. ft (b) express the equation of motion in the form x(t) = ae−λt sin ω2 − λ2 t + ϕ , which is given in (23) of section 3.8. (round ϕ to two decimal places.) x(t) = ft (c) find the first time at which the mass passes through the equilibrium position heading upward. (round your answer to three decimal places.)