Use the position function s(t) = −16t2 + v0t + s0 for free-falling objects. a ball is thrown straight down from the top of a 800-foot building with an initial velocity of −20 feet per second. (a) determine the position and velocity v(t) functions for the ball. s(t) = −16t2+800 v(t) = −32t (b) determine the average velocity, in feet per second, on the interval [1, 3]. ft/s (c) find the instantaneous velocities, in feet per second, when t = 1 and t = 3. v(1) = ft/s v(3) = ft/s (d) find the time, in seconds, required for the ball to reach ground level. (round your answer to three decimal places.) s (e) find the velocity of the ball, in feet per second, at impact. (round your answer to one decimal place.) ft/s