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Homework Help: Vectors help

  1. Dec 28, 2008 #1
    1. The problem statement, all variables and given/known data

    ST= 2TP. If [tex] \overrightarrow{TP}=a[/tex] , [tex] \overrightarrow{PQ} = b [/tex] and [tex] \overrightarrow {QR} = C [/tex] express in terms of a, b and c

    a) [tex] \overrightarrow{RT} [/tex]

    b) [tex] \overrightarrow{ST} [/tex]

    c [tex] \overrightarrow{SR} [/tex]

    http://www.mathhelpforum.com/math-help/attachments/advanced-applied-math/9244d1230495606-mechanics-help-untitled.jpg [Broken]

    can anyone help me with this question please, I have attached the diagram

    thank you!
    2. Relevant equations
    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Dec 28, 2008 #2


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    Join R to T and you'll have an enclosed polygon and if all the vector arrows follow the same direction, the resultant is zero.

    so TP+ PQ+ QR + RT=0. You can now find RT.

    (Triangle law, parallelogram law, polygon law)
  4. Dec 28, 2008 #3
    so does RT = a+b+c ?

    and how do i find ST and SR?
  5. Dec 28, 2008 #4


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    No … TR = a+b+c.
  6. Dec 28, 2008 #5
    okay , can you explain that? what does RT equal?
  7. Dec 28, 2008 #6


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    ok … TR is the vector from T to R …

    you can either go direct,

    or you can go any indirect route (that's the way "vector addition" works), provided the arrows follow you all the way.

    If you go from R to T, the arrows don't follow you.

    If you go from T to R, they do. :smile:
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