During a sports drill a runner starts from a flag post, runs straight 100m east to a cone, and then immediately runs straight back to the flag post along the same line, taking a total time of 40s.
(i) Explain the difference between the terms distance and displacement for the complete drill.
(ii) If the runner claims that her average speed was 5m/s, verify this statement with suitable calculations.
(iii) State the numerical value of her average velocity for the complete drill and justify your answer conceptually.