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.
a. (i) Explain the difference between the terms distance and displacement for the complete drill.
b. (ii) If the runner claims that her average speed was 5m/s, verify this statement with suitable calculations.
c. (iii) State the numerical value of her average velocity for the complete drill and justify your answer conceptually.