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Homework Help: Vector equations

  1. Feb 6, 2015 #1
    1. The problem statement, all variables and given/known data
    What is the significance of each vector forumula? Which one is used for what and why? What is the purpose of the symmetric function?

    2. Relevant equations
    1) r = r0 + tv
    2) r(t) = (1 - t)r0 + tr1
    3) Symmetric equation

    3. The attempt at a solution
    My textbook introduced me to the first formula write equations for vectors, which I understand. Later it introduced segments and modified the first equation to the second one, without any clear explanation. I don't understand why seperate formulas are needed for vectors and segments. Finally, my textbook concluded that chapter by eliminating the parameter t and getting the "symmetric equation". What is the purpose of that equation? Thank you so much. This is so confusing for me.
  2. jcsd
  3. Feb 6, 2015 #2


    Staff: Mentor

    The first one describes a particle at position r0 at time t0=0 moving with velocity v. The r then is the position at any time t of the particle.

    The second one is saying given a particle at r0 and then at r1 you can determine its position at any time t.

    Notice when you rearrange the terms a bit you get r0 + (r1 - r0) t so the (r1 - r0) factor is the velocity v from the first equation.

    I'm not sure about the symmetric equation...
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