Answer the following questions related to the quantities average speed and average velocity.
a. (i) Define average speed and average velocity.
b. (ii) Give one concrete example of a journey in which the average speed is non-zero but the average velocity is zero. Explain your answer briefly in 3–4 lines.
c. (iii) Derive, step by step, the numerical conversion factor between 1km/h and m/s. Show how the basic SI units of length and time lead to this factor.