Question

A train 400 m long is running at a speed of 40km/h. How long will it take to cross a bridge 800m long?

Answer 1

It will take 80m/h to cross the 800m long bridge

Answer 2

Question:

A train 400 m long is running at speed of 40km/h. How long will it take to cross a bridge 800 m long?

Solution:

• Length of train = 400 m

• Length of bridge = 800 m

• Total distance to cross (end to end) = 400+800 = 1200 m

Speed in m/s

40×1000/3600

100/9 m/s

Total time to cross the bridge =

distance / speed

1200/100/9

108 sec

1 min 48 sec

Therefore,

1 min 48 seconds are required to cross the bridge of 800m.