Question

a train takes 6 hours to complete a journey at a speed of 72 km/h . how long will another train takes to complete the same journey if the speed is 15m/s​

Answer 1

Solution,

Here,

time taken = 6hrs

speed = 72km/hr

= 72 × 1000m

1 × 60 × 60

= 72000m

3600

= 20m/s

Then,

distance = speed × time taken

= 20m/s × 6 × 60 × 60

= 20 × 21,600

= 4,32,000metres

Given,

speed = 15m/s

distance = 432km OR 4,32,000metres

time taken = ?

Now,

Time taken = distance

speed

= 4,32,000

15

= 28,800seconds

Finally,

= 28,800

60×60

= 8 hours..

Hence,

It takes 8hours to complete the same journey , if the speed is 15m/s...

Hope it helps you....