Question

A
MAN GOES TO MARKET WITH SPEED OF 6 60 kmph
AND RETURN WITH SPEED OF 20 KMPH CALCULATE
HIS AVERAGE VELOCITY
​

Answer 1

Let us assume that the distance covered by the man is x km.

Case 1)

Man goes to market with a speed of 60 km/hr.

Now, Time = Distance/Speed

t1 = x/60 hr ............(1st equation)

Case 2)

Man return with a speed of 20 km/hr.

t2 = x/20 hr ..............(2nd equation)

We have to find the average speed of the man.

Average speed is defined as the ratio of total distance travelled with respect to total time taken. Whereas average velocity is defined as the ratio of total displacement with respect to the total time taken.

Assume that the man starts from home to market. As said in question he goes to market with a speed of 60 km/hr and then returns back. Means his starting and initial points are same.

So, the Displacement of the man is 0 km.

Therefore, the average velocity of the man is 0 km/hr.

Answer 2

★ Diagram:

Let initial point be A & final point be B

A. _______________ . B

––––– Going –––→

←––– Returning –––

Here, the man is travelled and returned to the same point so displacement = 0

Given:

• Speed of man = 60km/h
• Returning Speed = 20km/h

To find:

• Average velocity

Solution:

Method 1:

Let distance travelled be x

Total distance = Distance travelled + returned

Total distance = x + x

Total distance = 2x

Total time = Time when going + returning

Let

• Time when travelling be t1
• Time when returning be t2

Now,

Finding time using

Time = Distance/Speed

→ t1 = x/60

→ t2 = x/20

♦ Total time = t1 + t2

♦ Total time = x/60 + x/20

♦ Total time = x/15

Now,

Average velocity = Displacement/Total time

Average velocity = 0/(x/15)

Average velocity = 0/x

Average velocity = 0km/h

Hence, average velocity = 0km/h