Question

Two trains of lengths 150 metres and 225 metres respectively are running in opposite
direction on parallel track with the speed of 35 km/hr and 37 km/hr respectively. In what time
will they cross each other?





Answer sheet answer is 75/4 ​

Answer 1

Question: Two trains of lengths 150 meters and 225 meters respectively are running in opposite  direction on parallel track with the speed of 35 km/hr. and 37 km/hr. respectively. In what time  will they cross each other?

Given:-

Lengths of two trains = 150 metres and 225 metres respectively.

They are running in opposite  direction on parallel track.

Speed of trains = 35 km/hr and 37 km/hr respectively.

To find:-

In what time  will they cross each other?

Solution:-

From the question we come to know,

When two trains are moving in opposite direction,

→The relative speed of the faster train w.r.t the slower train = Sum of their speeds.  

Sum of their speeds:-

➺35+37

➺72kmph  

Converting units:-

To convert km/hr to m/s,we need to multiply the number by 5 and divide by 18.That is,

➺72kmph=$72\times \frac{5}{18}$m/s

 = 20m/s.

Hence,  

The relative speed is 20m/s.  

And,

 

• Distance travelled=Sum of the lengths of the two trains

➺Distance travelled = (150+225)

➺Distance travelled = 375

Using the formula,

$\textsf{Time} =\frac {Distance}{speed}}$

Putting values,

➺Time = 375 /20

= 18.75s.

Hence,they will cross each other at 18.75s.

Answer- 18.75s.