Question

20. A train 700 m long is running at 72 kmph. if
it crosses a tunnel in 7 minute, length of the
tunnel is:​

Answer 1

Answer:

500

Step-by-step explanation:

Length of train = 700 m

Length of tunnel = X (let)

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

Speed = 72 kmph = (72*5)/18 = 20 m sec.

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

Now,

S*T = D

20 *60 = 700 +X

X = 1200 - 700 = 500

Length of tunnel = 500 m.

Answer 2

Answer:

Let the length of the travelled by the train be x

Speed of the train = 72 kmph = 72 × 5 = 20 m/s

18

Train crosses the tunnel in 7 min

= 7 × 60 = 420 sec.

W.K.T

Speed = Distance

Time

20 = x

420

x = 20 × 420

x = 8400 m

We need to subtract the length of the train.

So length of the tunnel = Distance travelled by the train - length of the train

= 8400 - 700 Length of the tunnel = 7700 m