The velocity of a particle traveling in a straight line is given by v = (6t - 3t'i [m/s], where t is in seconds. if x = 0 [m] when t = 0 [s), (a) determine the particle's acceleration and position when t= 4 ]. (b) is the particle speeding up or slowing down at t = 4 [s]? (c) sketch the motion of the particle during the 4 seconds. (d) how far has the particle traveled during the 4.s time interval, and what is its average speed?