Question

A car travels a certain distance with a speed of 60 km/h and then returns back to the starting point with a speed of 50 km/h . Find the average speed and average velocity of the body .

Answer 1

Let S be the distance between A and B. Total distance covered in the round trip is 2S.

Time taken to go from A to B at speed 40 km/h is S/60

Time taken to return from B to A at speed 120 km/h is S/50

So, total time of travel is = S/60 + S/50 = 11S/300 = 11S/300

Thus average speed = 2S/(11S/300) = 600/11 km/h = 54.55 km/h

Average velocity = 0, since, net displacement in the round trip is zero.