A train starts from station S and travels 1500m due west to signal P in 60s. It halts at signal P for 30s waiting for clearance and then moves 500m due east to stop at station Q in the next 40s.
(i) Draw a neat labelled sketch showing the positions S, P and Q on a straight line and mark all distances and directions.
(ii) Compute the total distance covered by the train from S to Q.
(iii) Determine the net displacement of the train from S to Q, stating its magnitude and direction.
(iv) Calculate the average speed of the train for the entire journey, including the halt at P.
(v) Calculate the average velocity of the train for the entire journey and explain clearly why its numerical value is different from the average speed obtained in part (iv).