A battery-powered toy cart starts from rest on a straight track. It first speeds up uniformly for 6 s until it reaches a velocity of 3 m/s, then maintains this velocity for the next 4 s, and finally slows down uniformly to rest in another 5 s.
(a) Draw a neat, labelled velocity–time graph for the entire motion described above.
(b) Explain, with reference to your graph, whether the cart is accelerating, moving with uniform velocity, or decelerating in each of the three time intervals.
(c) State the interval(s) during which the acceleration of the cart is zero and justify your answer from the graph.