Question

a train passes two bridges of lengths 210m and 122 in 25 and 17 seconds respectively the speed of the train is 39.6km/hr let us find the length of the train​

Answer 1

Step-by-step explanation:

Answer is 11 m/sec

Solution:

Let length of train be x

As speed of train is uniform then speed to cross platform and bridge is equal. Here catch is that when you completely cross platform or bridge you need to cover the length of train as well. As train will be considered to have crossed when full train has crossed the platform or bridge.

So,

(122+x) / 17 = (210+x) / 25

x=65 m

Now put in any equation and you will find the speed. For example (122+65) / 17 = 11 m/sec.