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Homework Help: Finding the second displacement from the first and resultant

  1. Jan 19, 2014 #1
    1. The problem statement, all variables and given/known data

    A particle undergoes two displacements. The first has a magnitude of 147 cm and makes an angle of 115 degrees with the positive x axis. The resultant displacement has a magnitude of 188 cm and is directed at an angle of 29.6 degrees to the positive x axis.

    a) Find the magnitude of the second displacement.
    b) Find the direction of the second displacement (with positive measured counterclockwise from the x axis, between the limits of -180 degrees and 180 degrees).

    2. Relevant equations

    Not entirely sure.



    3. The attempt at a solution

    I've done similar problems to this (finding the resultant displacement) but I don't know how to find the second displacement. I tried looking this problem up and couldn't find any help that led to the right answer.
  2. jcsd
  3. Jan 19, 2014 #2


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    Homework Helper

    if you're ok with using just components, then x1+ x2 = xtotal ... gives you x2 since you know x1 and xtotal.
    similarly, y1 + y2 = ytotal gives you y2 since you know y1 and ytotal.

    Don't forget Pythagoras, if they want magnitudes!
  4. Jan 19, 2014 #3
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