Question

A policeman is standing on a railway bridge which is 60 metres long.He finds that a train crosses the bridge in 4 1/2 seconds but himself in 2 seconds What is the length of the train and it's speed? ​

Answer 1

Answer:

the length of train is 48m.

Step-by-step explanation:

Solution

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Verified by Toppr

Let x and v be the length and speed of train.

Length of platform =60m

Time taken by the train to cross the bridge =4

2

1

=

2

9

s

Time taken by the train to cross the policeman =2s

Now,

When the train crosses policeman-

t=

s

x

⇒s=

2

x

When the train crosses platform,

t=

s

x+60

2

9

=

2

x

x+60

⇒

2

9

×

2

x

=x+60

9x=4x+240

⇒9x−4x=240

⇒x=

5

240

=48m

Hence the length of train is 48m.