Question

a train 100m long is two cross a river bridge of 800m what Will it take cross the bridge?given that the trains moves with a constant of 30km/h?​

Answer 1

To cross bridge completely engine of train has to travel 100m (ie it’s length) more in addition to bridge length of 800m.

So total distance to be travelled = 900m

Speed = 30 km/hr

= 30 × (5/18) m/s

= 75/9 m/s

= 8.3333 m/s

Therefore

Time taken = distance/speed

= 900/8.333

= 108.04 seconds or 1 min 48.04 seconds.

Answer 2

1. speed of train is 30km/h

then train is 30÷18×5=8.33m/s

time =total distance\time

800m+100m/8.33

=900/8.33

=108.04sec.(1min48.04sec.)