Question

A train that is 280 metres long travelling at a uniform speed, crosses a platform in 60 seconds and passes a man standing on the platform in 20 seconds. What is the length of the platform in metres?

Answer 1

The train with length 280m passes by a man standing on platform in 20s. The speed of train is

V = 280/20 = 14m/s

Let the length of platform be L

(L + 280 )/60 = 14

L + 280 = 60×14

L = 840 - 280

L = 560 m

Thanks

Answer 2

Given :-    

• Length of train is 280 m
• Crosses a platform in 60 sec  
• Crosses a man standing on platform in 20 sec  
• It is moving at uniform speed  

To Find :-  

• Length of the platform  

Solution :-  

~Here , we’re given the length of train and time taken by it to cross a platform and a man . As the speed is uniform , it’s speed will be same to cover both the distances and we’re given the time taken . From here we can easily find the distance of the platform by putting the values in the formula of finding the speed.

 

Let the length of the platform be ‘ x ‘  

Speed of train while crossing the man and platform is same and we know that,  

$\sf Speed = \dfrac{Distance}{Time}$

While crossing the platform ::

$\sf speed = \dfrac{280+x}{60}$

While crossing the man ::

$\sf speed = \dfrac{280}{20}$

As the speed is equal, the equation formed will be  

$\sf \implies \dfrac{280+x}{60} = \dfrac{280}{20}$

$\sf \implies \dfrac{280+x}{60} = 14$

$\sf \implies 280 + x = 14( 60 )$

$\sf \implies 280 + x = 840$

$\sf \implies x = 840- 280$

$\sf \implies x = 560$

Therefore,  

Length of the platform is 560 m