A scooterist starts from point A, rides 40m due east in 20s to reach point B, and immediately returns to point A along the same straight line in the next 20s. Answer the following questions.
(i) Define average speed and average velocity.
(ii) Calculate the total distance travelled during the whole journey.
(iii) Determine the total displacement for the whole journey.
(iv) Find the average speed of the scooterist for the complete trip.
(v) Find the average velocity of the scooterist for the complete trip, stating its magnitude and direction. Explain why this value differs from the average speed obtained in part (iv).