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Homework Help: Vector addition

  1. Sep 30, 2010 #1
    1. The problem statement, all variables and given/known data
    A vector of magnitude 20 is added to a vector of magnitude 25. The magnitude of this sum might be:
    a. zero
    b. 3
    c. 12
    d. 47
    e. 50


    2. Relevant equations
    c ^2 = a^2 + b^2


    3. The attempt at a solution

    I was not entirely sure on what to do. I tried using the Pythagorean theorem to find the resultant of the 2 vectors and got 32. ( c ^2 = 20^2 + 25^2).
    The answer by the way is C.

    Thanks!
    Joe
     
  2. jcsd
  3. Sep 30, 2010 #2
    Try do add the vectors in different ways. Then you will get a possible maximal and a minimal value for the magnitude of the resulting vector. All but one possible answers are outside of this region.
     
  4. Oct 1, 2010 #3
    okay. I got it. The max magnitude of their addition would be when they are parallel in the same direction. mag would = 45. The min would be when they are parallel in the opposite direction. mag would = 5. Therefore the answer is 12. Thanks!
     
  5. Oct 1, 2010 #4
    Good.
     
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