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Negative vector why isn't it choice 4.

  1. Feb 5, 2016 #1
    1. The problem statement, all variables and given/known data

    If the vector B⃗ has a magnitude of 45.0 m and makes an angle of 60.0 ∘ with the +x axis, the vector -B⃗
    choices:
    1. has a magnitude of 45.0 m
    2. has the same direction as B⃗ , but a magnitude of − 45.0 m
    3.makes an angle of − 60.0 ∘ with the +x axis
    4. has the opposite direction of B⃗ and a magnitude of − 45.0 m
    2. Relevant equations


    3. The attempt at a solution
    y axises
    I -------45.0m diagonal
    I 60 Degrees angle
    <-(-x)-------------------+x--axises---->
    I
    I
    -y axises
     
  2. jcsd
  3. Feb 5, 2016 #2
    What does it mean for magnitude to be negative? Does it make sense for the length of a vector to be negative?
     
  4. Feb 5, 2016 #3
    Oh . I see. Thanks you . Magnitude can't be negative
    So is it -60 with respect to the x causes because it's now in the third quadrant since the vector b negative is when you reverse the head and the tail of the arrow.
     
  5. Feb 5, 2016 #4
    It would be -120. Not -60
     
  6. Feb 6, 2016 #5
    Super clear ... thank you very much for your help.
     
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