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Where The Smoke Blows (Posted on 2003-06-20) Difficulty: 2 of 5
An electric passenger train goes at 73 km/h in the direction of south east. A wind is blowing from the south at 31 km/h.

What is the direction that the smoke from the train is blowing and at what speed?

  Submitted by Jonny Doe    
Rating: 2.0000 (12 votes)
Solution: (Hide)
The correct answer is of course that electric trains do not produce any smoke...

...but if it did, the problem is still far from straightforward. While one's initial reaction is to do vector arithmetics on the two velocities (73 to the SE and 31 to the N), that would not yield an accurate answer.

Such reasoning would work well for determining the velocity of a boat swimming in a current, but in the case of smoke (if such were to be produced by an electric train), it would not maintain the train's original velocity, since it would lack momentum (smoke, we will assume has practically no mass).

As such, the emmited smoke will immediately start moving with the wind, going north at 31 km/h, in a line extending further and further southwest.

Comments: ( You must be logged in to post comments.)
  Subject Author Date
as the wind blowsdex2007-09-24 15:07:25
answerK Sengupta2007-03-20 12:34:44
the wind blows nowhere....lisa2006-05-29 18:12:12
omg easyJak Dakars2005-03-25 22:10:41
come on!Janelle2005-02-06 01:50:36
No SubjectJoshua2004-11-01 15:32:11
No Subjectgreg2004-10-14 10:28:01
Some Thoughtsre: My solutionelliana2004-04-16 15:12:50
SolutionMy solutionkrdmt5_0002003-12-16 16:06:26
Solutionoldie but goodietammy2003-07-26 08:07:26
Questionre(4): Old SmokieChris2003-06-22 23:41:32
re(4): Old Smokienellie2003-06-22 05:19:51
re(3): Old Smokieanoop2003-06-21 21:26:16
DERR RETARDEDChaz2003-06-21 16:15:28
re(2): Old Smokienellie2003-06-21 07:29:54
re: Old Smokieanoop2003-06-21 05:37:56
re: We got itLewis2003-06-21 00:22:41
Some ThoughtsWe got itPickels2003-06-20 18:03:29
No Subjectgrace2003-06-20 11:20:28
Old Smokienellie2003-06-20 09:09:36
SolutionSolutionDuCk2003-06-20 05:16:15
Let me think...Chris2003-06-20 03:58:44
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