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Homework Help: Questions on Vectors

  1. Sep 4, 2007 #1
    1. The problem statement, all variables and given/known data

    I have two questions on vectors:
    1) Does the magnitude of a vector vary depending on how one chooses a reference frame?
    2) Can a component of a vector be negative?

    2. Relevant equations


    3. The attempt at a solution

    1) No, because regardless of the reference frame, the magnitude is always the same?
    2) Yes, say if the vector points -y or -x or -z
  2. jcsd
  3. Sep 4, 2007 #2
    1) is wrong, I think.

    because what if frame of reference is also moving at the velocity of v, where v is the velocity of the object being observed?..
  4. Sep 4, 2007 #3
    Yeah, that makes sense. But doesn't the vector remain the same? For example, if I have a vector of 5m/s north, it remains that vector whether or not the reference frame is stationery earth or a train moving at 10m/s north... Or is the question asking like the magnitude of the object and not the vector? Sorry, I'm confusing.
  5. Sep 4, 2007 #4
    I am not sure if they are asking for resultant vector, or that original vector... (refer to those relatve motion questions)
    mag. of the resultant != mag of org

    yea, otherwise org. vectors remains that same vector unless some force is applied to it..
    Last edited: Sep 4, 2007
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