Question

A man standing on a platform 225m long notices that a train travelling at a uniform speed passes him in 6s and passes by the platform in 21s find (1)the length of the train and (2) the speed of the train

Answer 1

Step-by-step explanation:

Suppose x be the length of the train.

Length of the platform = 225 m

So total distance to be covered to pass the platform = (225 + x) m

And time taken to pass the platform = 21 sec

Also time taken to pass the man standing on the platform = 6 sec

so, speed of train = (225+x)21 = x6

⇒(225+x)21 = x6⇒6(225+x) = 21x⇒1350+6x = 21x⇒21x−6x = 1350⇒15x = 1350⇒x = 135015 = 90

Therefore length of the train is 90 m.

And speed of train = 906 = 15 m/sec