A train is 100m long and is moving with uniform velocity of 45 km/h. The time it will take to cross a bridge 1km long is nearly?

We are given a train 100m long that is traveling at a uniform rate of 45 km/h. We are asked to find the time required to cross a bridge 1 km long.

We assume that the question means for the entire train to get across the bridge. Envision the engine at the very front edge of the bridge. In order for the entire train to cross the bridge, the engine will travel 1.1 km (the first km to get the engine across the bridge with the additional 100 m=.1 km to get the last car across the bridge).

So, the distance traveled will be 1.1 km at a rate of 45 km/h; to find the time we use d=rt or t=d/r where t is time in hours, d is the distance in km and r is the rate in km/h.

t=1.1/45 ==>

As a fraction this is 11/450 hours, or 1 and 7/15 minutes or approximately 1.47 minutes.