Question

body travel from A to B at 60m/s and B to A at 80m/s calculate average speed and average velocity

Answer 1

Motion

Let the distance a d

So the time taken to move from A to B will be a/60 s (as speed = distance / time)

And time taken to move from B to A will be a/80 s (as the distance is constant)

And the total distance = (a + a) m = 2a m
Total displacement = 0 (as the body is at the same position where it had started its journey)

So avg. speed = (total distance)/(total time taken)
= 2a/{(a/60) + (a/80)} m/s
= 2a/{(4a+3a)/240} m/s
= 2a/(7a/240) m/s
= 480/7 m/s
= 68.6 m/s (estimately)

A caution never try to add the velocities and divide them by two in this situation because here the times are different.

And avg velocity will be 0 as the displacement is zero.

That's it
Hope it helped