The function s(t) describes the motion of a particle along a line. s(t) = t2 − 14t + 22 (a) find the velocity function v(t) of the particle at any time t ≥ 0. v(t) = 2t−14 (b) identify the time interval(s) in which the particle is moving in a positive direction. (enter your answer using interval notation.) (7,∞) (c) identify the time interval(s) on which the particle is moving in a negative direction. (enter your answer using interval notation.) (−7,7) (d) identify the time(s) at which the particle changes direction. (enter your answers as a ,-separated list.) t =