A train takes 1 minute to cross a stationary pole. How much time (in seconds) will it take to cross a bridge whose length is twice that of the train?

180

Let the length of train be D

Speed of train = \(\frac{Distance}{Time}\)

Distance = length of train

= \(\frac{D}{60}\)

According to question ,

Length of the bridge = 2D

Now , Total distance = 2D + D

Speed of train = \(\frac{3D}{Time}\)

As , Speed is same in both the cases .

\(\frac{D}{60}\) =  \(\frac{3D}{Time}\)

Time = 60 × 3 = 180 seconds

So , Train will take 180 seconds to cross the bridge.