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Homework Help: Vector addition

  1. Sep 26, 2010 #1
    1. The problem statement, all variables and given/known data
    A train at a constant 47.0 km/h moves east for 44 min, then in a direction 57.0° east of due north for 27.0 min, and then west for 61.0 min. What are the (a) magnitude (in km/h) and (b) angle (relative to north, with east of north positive and west of north negative) of its average velocity during this trip

    2. Relevant equations
    vaverage=displacement/total time

    3. The attempt at a solution
    For part (a) I found the x and y components of the displacement vector (x-component was 4.2645491 and y-component was 11.51911559056) and I got 12.28317560
    Then I plugged that in to the vaverage equation:
    12.28317560/1.2966=5.59190367 Km/h
    I know I got this one right because the wileyplus system game me the checkmark

    For part (b)
    arctan (4.2645491/11.51911559056)=20.31530698
    For this part I keep getting the message that my answer is incorrect, I don't know what I'm doing wrong
  2. jcsd
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