Question

A boy goes from A to B with a velocity of 20m/min and comes back from B to A with a velocity of 30 m/min.the average velocity of the boy during the whole journey is :

24m/ min

25m/min

zero

20m/min

​

Answer 1

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

To find: We have to find the average velocity of the boy.

Solution:

Let the distance between A and B is D meter.

A boy goes from A to B with a velocity of 20m/min.

So the time =D/20

He comes back from B to A with a velocity of 30 m/min.

So, the time= D/30.

Total time=D/20+D/30

=5D/60

Total distance traveled by the boy =2D.

Average velocity of the boy is a ratio of total distance to total time.

$\frac{2D}{ \frac{5D}{60} } \\ = \frac{2 \times 60}{5} \\ = 24$

The average velocity of the boy during the journey is 24m/min.

Answer 2

Answer:

Zero

Explanation:

As the initial and final position is the same the displacement is zero which means that whatever the time is the avg. velocity will come out to be 0

avg velocity = total displacement/total time

avg velocity = 0/d/20+d/30

avg velocity = 0