15. When an object is dropped, the distance it falls in t seconds, assume negligible air resistance, is given by 5(t) = 16132 , Where s(t) in feet. Suppose a medic's reex hammer falls from a hovering helicopter. Find (a) how far the hammer falls in 3 sec, (b) how fast the hammer is travelling 3 sec after being dropped, and (c) the hammer's acceleration after it has been falling for 3 sec