Question

a car travels from A to B at speed of 20km h-1 and returns at a speed of 30km h-1. the average speed of the car for the whole journey is.

Answer 1

let the distance travelled be x
here take A as origin and move with velocity 20 m/s in direction of B and after now take B as origin and move in direction of A with velocity 30 m/s so displacement is zero
average velocity = total displacement / total time or (v+u)/2
but here displacement is zero so average velocity is also zero