Question

a body moved from point A to B, travelling some distance with speed 80km/hr. it moves back from B to A with speed 40 km/hr. find the average velocity of the body for entire journey.​

Answer 1

Answer:

Average velocity of the body = 0 km/h

Step by step explanations :

given that,

a body moved from point A to B, travelling some distance

with speed 80 km/hr.

it moves back from B to A

with speed 40 km/hr.

now,

Average velocity = displacement/time

here,

displacement = 0 m

so,

Average velocity = 0 m/s

________________

Extra information :

Average speed :

let the distance between A and B be d

here,

time taken to cover d from A to B

= d/80 h

and,

time taken to cover d from B to A

= d/40 h

now,

Average speed =

total distance travelled/total time taken

here,

total distance travelled = 2d

[from A to B and then from B to A]

total time taken = d/80 + d/40

= (d + 2d)/80

= 3d/80 h

now average speed

= 2d/(3d/80)

= 160d/3d

= 53.3 km/h

so,

Average speed of the body

= 53.3 km/h

Answer 2

Answer :-

$A_v = 0 m/s$

Given :-

A body moves from point A to B , travelling with speed of 80 km/hr.

And back from B to A with speed of 40 km /hr .

To find :-

The average velocity for entire journey.

Solution:-

Actually , this question is just for watching your concepts.

See , how

Displacement → It is the shortest distance between the final and initial position covered by the body.

A/Q

The body come back to its original position so , it's displacement will be 0.

Now,

Average velocity →It is defined as the ratio of the total displacement covered by the body to total time taken.

If , displacement will be 0 then , average velocity will also be 0.

→$A_v = \dfrac{S}{T}$

→$A_v = \dfrac{0}{T}$

→$A_v = 0 m/s$

hence,

Average velocity of the body will be 0 m/s.

Note → It doesn't matter what is its given speed because the body come back to its original position and thus displacement becomes 0.