Question

A train 100 m long is to cross a river bridge of length 800m. What time will it take to cross the bridge?given that the train moves with aconstant velocity of 36km/h .

Answer 1

time is distance divide by speed
$800 \div 36$
22sec

Answer 2

Total distance required for the train to cross the bridge is,

d = (100 + 800) m = 900 m

The speed of the train is,

v = 36 km/h =36 × 5 / 18 = 10 m/s

Hence the time taken to cross the bridge is,

t =900 / 10 = 90 s.