GATE2014 EC-1: GA-8

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?

Comments

1.When a train cross a pole or a person then it covers the distance equal to its length.(length of train)

2.When a train cross another train or a platform  than it covers distance equal to sum of both length(length of train+length of platform)

Answer 1

Speed of train$=280/20=14m/s$

Let $L$ be the length of platform

$280+L$  covered in $60s$

$\frac{280+L}{14}=60$

$280+L=840$

$L=840-280$

$L=560m$

Answer 2

For a train to cross a person, it takes 20 seconds for its 280m. so d=s*t  then 280=s*20 then we get s=14m/s and in

 60 seconds. Total distance travelled should be 840 bcz  d=14*60 =840. Including 280 train length so length of plates =840-280=560

so answer is 560