When an object is​ dropped, the distance it falls in t​ seconds, assuming that air resistance is​ negligible, is given by ​s(t)equals=4.9054.905t2 where​ s(t) is in meters​ (m). If a stone is dropped from a​ cliff, assuming that air resistance is​ negligible, find the velocity and acceleration of the stone after it had been falling for 1515 sec.