The function s = f(t) gives the position of a body moving on a coordinate line, with s in meters and t in seconds. s= - t3+ 7t 2 - 7t. Ost=7 Find the body's speed and acceleration at the end of the time interval. A 7 m/sec, 0 m/sec2 B 56 m/sec, -28 m/sec2 56 m/sec, -7 m/sec2 -56 m/sec, -28 m/sec2