Question

A person is walking parallel to the railway line at the speed of 5 kilometre per hour a train travelling in opposite direction at 49 km per hour fast him in 12 seconds find the length of the train

Answer 1

Correct Question:-

• A person is walking parallel to the railway line at the speed of 5 km/hr a train travelling in opposite direction at 49 km/hr passes him in 12 sec. find the length of the train.

Given data:-

—› Speed of person = 5 km/hr

—› Speed of train = 49 km/hr

—› Time taken by train to pass from man is = 12 sec .......( 1 )

Solution:-

Let, x be the speed of person and y be the speed of train.

Here,

—› Relative speed of person and train

= { x + y }km/hr = {5 + 49}km/hr = 54 km/hr

{We need to convert 54 km/hr in m/s}

Now,

—› 54 km/hr = [{54 × 1000}/{ 60 × 60 }]m/s

—› 54 km/hr = [54000/3600 ]m/s

—› 54 km/hr = [540/36]m/s

—› 54 km/hr = [540/36]m/s

—› 54 km/hr = 15 m/s .....( 2 )

We know the formua of speed:

—› speed = distance/time

—› distance = speed × time

Here, we take distance as length to calculate the length of the train.

—› length = speed × time

{ from ( 1 ) & ( 2 )}

—› length = 15 × 12

—› length = 180 m

Hence,the length of the train is 180m

{Note: 180m = 0.18 km}