A man standing on a railway bridge which is 180 m long. He find that a train cross the bridge in 20 seconds but cross him in 8 seconds. Find the length of the train and its speed.

Answer 1

let L be the length of the train.
speed=distance/time=L/8 sec

speed=(180+L)/20

L/8=(180+L)/20
2.5L=180+L
1.5L=180
L=120m
speed=120/8=15 m/s