A ball is projected vertically upward from ground level with a speed of 15 m/s. Air resistance is negligible and the acceleration due to gravity has magnitude 9.8 m/s² (take upward as positive).
Answer the following:
(i) Draw the velocity–time graph for the motion from the instant of projection until the ball returns to the point of launch.
(ii) Using the graph, find the time taken to reach the highest point and the total time of flight.
(iii) On the same graph, shade separately the areas representing displacement during ascent and descent, and comment on their signs.
(iv) Using the graph, determine the net displacement of the ball after the complete flight and justify your answer physically.