Question

What is the time taken by a 100 m long train travelling at a speed of 36 km/hr to cross a bridge of length 80 m?

• A. 36 sec
• B. 18 sec
• C. 20 sec
• D. 40 sec

Answer 1

The correct option is B

18 sec

Time taken = Distance travelled / Speed

Here, Distance = length of the train + length of the bridge = 100 m + 80 m = 180 m

Speed, here it is the speed of the train itself as the bride doesn't have any speed. but we have to convert it into m/s. So, $36\times \frac{5}{18}=10m/s$

So now, the time is taken by the train to cross the bridge (in seconds)= $\frac{180m}{10m/s}=18sec$