Question

A body goes from A to B with a velocity of 20 m/s and comes back from B to A with a velocity of 30m/s. The average velocity of the body during the whole journey is
(a) Zero. (b) 25 m/s. (c) 24 m/s. (d) none of these

Answer 1

total distance travelled =2X

total time taken =X÷20 + X÷30

==5X÷60

average velocity=total distance ÷total time

2X÷5X/60

=24m/s

Answer 2

Given :-

A  boy goes from A to B with a velocity of 20 m/s and comes back from B to A with a velocity of 30m/s.

To Find :-

Average velocity

Solution :-

Total displacement = 0 (Since initial and final points are same)

Let the distance be x

Case 1

Time = Distance/Speed

Time = x/20

Case 2

Time = Distance/Speed

Time = x/30

Now

Avg. velocity = Displacement/Time

Avg. velocity = 0/(x/20 + x/30)

Avg. velocity = 0