Question

a train 77m long is running at 60 km/hr if it takes 30 seconds to cross the tunnel then find the length of the tunnel

Answer 1

Length of train=77m

Speed= 60km/hr

=60×5/18=50/3m/sec.

Time to pass tunnel=30sec

Now total travelling distance=speed×time

= 50/3×30=500m

Now length of tunnel= (500-77)

=423m.

Answer 2

Given :

A train 77m long is running at 60 km/hr if it takes 30 seconds to cross the tunnel

To Find :

Find the length of the tunnel

Solution:

Length of train = 77 m

Let the length of train be x

Total distance =77+x

Speed of train = 60 km/hr

1 km = 1000 m

1 hour = 3600 sec

Speed of train = 60 km/hr =$60 \times \frac{1000}{3600}=\frac{50}{3} m/sec$

Time = 3 seconds

$Time = \frac{Distance}{Speed}\\3 = \frac{77+x}{\frac{50}{3}}$

50=77+x

x=27

Hence The length of tunnel is 27 m