If a function s(t) gives the position of a function at time t, the derivative gives the velocity, that is, v(t) = s (1). For the given position function, find (a) v(t) and (b) the velocity when t = 0, t = 4, and t = 7. s(t) = 20t- 10t + 5 (a) v(t) = (b) t=0; v(0) = t =4; v(4) = t=7; v(7) =