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Homework Help: HOW can I not get this?

  1. Sep 29, 2004 #1

    Alkatran

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    HOW can I not get this??

    5. [1pt] A sailboat tacking against the wind moves as follows: 2.8 km at 27° east of north, 4.7 km at 28° west of north, and 3.9 km at 28° east of north. The entire trip takes 4 h 25 min. What is the magnitude of the displacement of the sailboat at the end of the trip ?

    Translated: Add the vectors in the question.

    Current answer:
    /\x = 2.8*sin(27) + 4.7*sin(-28) + 3.9*sin(28) = .805 km
    /\y = 2.8*cos(27) + 4.7*cos(-28) + 3.9*cos(28) = 9.910 km
    /\d = sqr(/\x2 + /\y2) = 9.943 km = 9943m

    What's wrong?
     
  2. jcsd
  3. Sep 29, 2004 #2
    Looks like you've got a math error. try emtering it into your calculator again. I get a little over 10 when I do it BTW.
     
  4. Sep 29, 2004 #3

    Doc Al

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    Staff: Mentor

    Check your arithmetic. I get (slightly) different answers for [itex]\Delta x[/itex] and [itex]\Delta y[/itex].
     
  5. Sep 29, 2004 #4

    Alkatran

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    Thanks, got it. At least it wasn't a logic error.
     
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