A car leaves town A (taken as origin) and drives 90 km due east to town B at a constant speed of 60 km h−1. It halts at B for 15 min and then travels back westward, stopping at town C which lies 30 km west of B, at a constant speed of 80 km h−1.
(i) Calculate the total distance travelled and the total time taken for the entire trip, including the halt.
(ii) Taking east as the positive direction, find the displacement of town C from town A.
(iii) Determine the average speed for the whole journey.
(iv) Find the magnitude and sign of the average velocity for the whole journey.