Question

a train 100m long is to cross a river bridge of length 800 M what time will it take to cross the bridge given train move with constant velocity of 36 km per hour

Answer 1

total distance (of train with river bridge)=100+800=900m
velocity =36km/hr=10 m/s
there for time take by the train to cross the bridge =
v=s/t
t=s/v
t=900/10
t=90 sec
t=1 min 30 sec

Answer 2

In this case is the total distance is

The length of bridge + The length of train.

=(800+100)m [according to the data mentioned in the question]

=900 m.

So,

The train travels;

36km in = 1 hr

36000 m in = 3600 sec

1 m in = 1/10 sec

900 m = 90 sec

So the needed time is approximately 90 sec or 1 minute 30 seconds.(answer)