Problems on Train and Running man is an important category in Time, Speed and Distance Topic.
All formulas used are taken from TSD, so if you are not aware of that chapter please read that first.
A jogger is running at 9 kmph, alongside a railway track, is 240 m ahead of the engine of a 120 m long train running at 45 kmph in the same direction. In how much time will the train pass the jogger?
Given: Speed of jogger = 9 kmph
Speed of train = 45 kmph
Length of train = 120 m
Jogger is 240 m ahead of train
Now, Speed of train relative to jogger = speed of train – speed of jogger =(45 – 36) kmph
= 36 kmph
= 36 x (1000/3600) m/sec = 10 m/sec
(since 1km = 1000m and 1hr = 60 x 60 sec = 3600 sec
Distance to be covered = distance jogger is ahead of train + length of train = 240 + 120 = 360m
Therefore, time taken = distance/speed 360/10 = 36 sec
Hence, train will pass through jogger in 36 sec.