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Homework Help: Magnitude of the vector

  1. Jan 27, 2007 #1
    I need help with the following questions-

    1. if a= 12i+16j and b=-24+10j, what is the magnitude of the vector C=2a-b?


    2.If the magnitude and direction of c are 2.5 cm and 80degree , and d[3.5cm,120degree] and e=d-2c then what is the direction of e, (to the nearest degree)?
     
  2. jcsd
  3. Jan 27, 2007 #2

    arildno

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    1. What information can you use in order to find the magnitude of a vector?
     
  4. Jan 27, 2007 #3
    you can use any formulas..
     
  5. Jan 27, 2007 #4

    arildno

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    So which one would YOU pick? :smile:
     
  6. Jan 27, 2007 #5
    I would use square root of (Ax)^2+ (Ay)^2
     
  7. Jan 27, 2007 #6

    arildno

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    Indeed, smart choice!

    So, what info are you at present lacking in order to calculate the magnitude?

    And:
    How can you OBTAIN that necessary information?
     
  8. Jan 27, 2007 #7
    no i got my answer as 64, just want to verify that, and I dnt have no clue about the second question
     
  9. Jan 27, 2007 #8

    arildno

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    Well, I don't bother to calculate myself all the way to 64 or to any other dumb number, I want to find out:
    HOW did you are at whatever number you got?
     
  10. Jan 27, 2007 #9
    can u help me with my second question
     
  11. Jan 27, 2007 #10

    arildno

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    The degrees are measured with respect to the positive x-axis.
    So:
    How can that help you?
     
  12. Jan 27, 2007 #11
    well i really dont know
     
  13. Jan 27, 2007 #12

    arildno

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    Well, how har the horizontal&vertical components of a vector related to the vector's magnitude and the angle the vector makes with the positive x-axis?
     
  14. Jan 27, 2007 #13
    i think it get calcuate arc tan of Ax/Ay
     
  15. Jan 27, 2007 #14

    arildno

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    No!
    Go back to your book, and read your definitions again.
     
  16. Jan 27, 2007 #15

    robphy

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    Check it for some special cases...
    What angle do you expect? and What do you get with your formula?
    - for a vector along the x-axis.
    - for a vector along the y-axis.
     
  17. Feb 1, 2007 #16

    berkeman

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    Moved from Advanced Physics to Intro Physics.
     
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