For this exercise, use the position function s(t) = −4.9t^2 + 160, which gives the height (in meters) of an object that has fallen for t seconds from a height of 160 meters. The velocity at time t = a seconds is given by lim t→a s(a) − s(t) a − t . When will the object hit the ground? At what velocity, v, will the object impact the ground?