SOLUTION: A slower bus has length 125 meters with speed 17 meters per second. A faster bus has length 140 meters with speed 22 meters per second. The slower bus is driving ahead, and the fas

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Question 1163592: A slower bus has length 125 meters with speed 17 meters per second. A faster bus has length 140 meters with speed 22 meters per second. The slower bus is driving ahead, and the faster bus is catching it up. How many seconds is it starting from the time the head of the faster bus is on the same spot as the tail of the slower bus to the time the tail of the faster bus is on the same spot as the head of the slower bus?
Answer by ikleyn(52756)   (Show Source):
You can put this solution on YOUR website!
.

To get the answer, you should divide the sum of the lengths by the difference of the speeds time = = 53 seconds.

Solved.

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Never saw so long buses.

Probably, you want to say "trains" instead of "buses".

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See closely related 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,

and especially the lesson marked (*) in the list as the most relevant to your problem.

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If you need a justification for the solution, here it is.

Use the coordinate system, connected with the slower "bus".

In this coordinate system, the slower bus is "unmoved", and the faster train moves with the speed which is
the relative speed of the buses, i.e. the difference of the speeds.

The rest is OBVIOUS.

In this problem, using this moving coordinate system is a standard method of the solution.