A car travels from city P to city Q, a distance of 60km, at a constant speed of 40kmh−1. Without any halt it immediately returns the same 60km back to city P at a constant speed of 60kmh−1. Answer the following.
a. (i) Calculate the total time taken for the entire journey.
b. (ii) Find the average speed for the complete trip.
c. (iii) Determine the magnitude of the average velocity for the whole motion and state its direction, if any.