A train takes one minute to cross a tunnel of length 700 meter at the speed of 72 km/hr. Find length of the train.

500m

Length of train = 700 m

Length of tunnel = X (let)

Time taken to cross the tunnel = 1 minute = 60 sec.

Speed = 72 km/hr

 = \(\frac{72\;×\;5}{18}\) m/sec

To cross the tunnel train needs to travel = Length of train + length of tunnel = 700 +X
Now,

distance = speed × Time

20 × 60  = 700 + X

X = 1200 - 700 = 500 m  

Length of tunnel = 500 m