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A passenger train travels at a speed of 72km/h. A man on the passenger train observes a goods train travelling at a speed
of 54km/h in the opposite direction . If the goods train passes him in 8 seconds, find the length of the goods train.
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The speed of the passenger train is 72 km/h = 20 m/s.
The speed of the goods train is 54 km/h = 15 m/s.
The passenger is moving with the speed 20 m/s + 15 m/s = 35 m/s relative to the goods train (since the trains moves in opposite directions).
Hence, the passenger sees the goods train before his own eyes during seconds, where L is the length of the goods train.
So, your equation is
= 8,
which gives the length of the goods train L = 8*35 = 280 m.
Answer. The length of the goods train is 280 m.
Solved.
For many other similar and closely related Travel and Distance problems see the lessons
- A train passing a telegraph post and passing a bridge
- A train passing a platform
- A train passing through a tunnel
- A light-rail train passing a walking person
- A train passing another train
in this site.
Also, you have this free of charge online textbook in ALGEBRA-I in this site
- ALGEBRA-I - YOUR ONLINE TEXTBOOK.
The referred lessons are the part of this textbook under the section "Word problems", the topic "Travel and Distance problems".
I understand that you are in rush, but I insistently recommend you to read these lessons.
It may happen this reading will be the best in your life.