Question

The speed of train is 30 km/hr .How long will it take to cross a signal if it's length is 25m?​

Answer 1

Given s =t+ 220/30 ••••••• (1)

and s= t + 325/39 ••••••• (2)

on solving (1) and (2), we get

39(t + 220) = 30(t + 325)

39t + 8580 = 30t + 9750

9t = 1170

t = 130 metres

Substitute in (1), we get

Speed = 130 + 220/30

= 350/30 =

= 11.66 m/sec

On converting it to km/hr, we get

S = 3600 * 11.66/1000

= 41.9

= ~42