Question

A train 700m long is running at speed of 72km/hr. It passes a tunnel in 1min, what is the length of the tunnel? ​

Answer 1

Solution:

Let the length of the tunnel be x mts

Speed of the train = 72 kmph = 72×51872×518 = 20 m/sec.

Train crosses the tunnel in 60 sec. (1min)

Therefore, (700+x)20=60(700+x)20=60

(i.e) Time taken to cover (700+x)(700+x)

(700+x)(700+x) = 60×2060×20

700 + x = 1200

x = 1200 - 700 = 500 mts.

Hope this helps you

Karthikrikky12 ♥️

Answer 2

passing of whole train includes time from when it's engine enters the tunnel upto when it's tail leaves the tunnel.

hence total distance covered by train is that covered by it's engine which is length of tunnel + length of train

let (L+700)

speed =(72*5)/18 =20 m/s

hence time * speed = 60* 20 = 1200m

hence length of train, 1200-700= 500m.