The velocity of an automobile starting from rest is given by the equation below, where v is measured in feet per second and t is the time in seconds. (Round your answers to three decimal places.) v(t) = 85t 8t + 14 (a) Find the acceleration at 5 seconds. ft/sec2 (b) Find the acceleration at 10 seconds. ft/sec2 (c) Find the acceleration at 20 seconds. ft/sec2