A train 700 m long is running at 72 kmph. If it crosses a tunnel in 1 minute, the length of the tunnel is

700 m 600 m 550 m 500 m

500 m

Speed in m/s = 72 x \(\frac{ 5}{ 18}\) m/s Speed in m/s = 20 m/s Let the length of the tunnel be x 20 = \(\frac{\text{700 + x}}{ 60}\) 1200 = 700 + x x = 500 m