Question

A train travels with the speed of 80km/h and returns with the speed of 90km/h. calculate average velocity and average speed of the train...please help...​

Answer 1

Answer:-

Let us assume that the train travels from A to B.

Let the Distance between A and B be d km.

Given:

It travels from A to B with the speed of 80 km/h.

We know that,

Time = Distance/speed

Hence,

→ Time taken by the train to travel from A to B = (d/80) hrs.

And,

The train returns from B to A with the speed of 90 km/h.

→ Time taken by the train to travel from B to A = (d/90) hrs

We know,

Average speed = Total Distance travelled/total Time

• Total distance covered = (d + d) = 2d km

• Total Time taken = (d/80) + (d/90) hrs

→ Average speed of the train = [2d] / [ (d/80) + (d/90) ]

→ Average speed of the train = 2d * [ 80 * 90 / (90d + 80d) ]

→ Average speed of the train = 2d * [ 80 * 90 ] / 170d

→ Average speed of the train = 84.7 km/hr.

Now,

Average Velocity = Total displacement/total Time

• Total displacement = d - d = 0 km

• Total Time = (d/80) + (d/90) hrs

→ Average Velocity of the train = 0 / [ (d/80) + (d/90) ]

→ Average velocity of the train = 0 km/hr

Therefore,

• Average speed of the train = 84.7 km/hr.

• Average velocity of the train = 0 km/hr.