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Homework Help: Power Question

  1. Sep 30, 2007 #1
    1. The problem statement, all variables and given/known data

    An object moves with a velocity of [4 m/s,-1 m/s, 3 m/s] and is acted on by a force of [-5 N, 0, +5 N]. What is the power of the energy transfer in this interaction?

    a. -35 W
    b. -5 W
    c. 0
    d. +5 W
    e. +35 W

    2. Relevant equations

    p = Fv

    3. The attempt at a solution

    Okay, so I'm trying to find p, and I'm given Fv, and I know that p = Fv. The problem is that it's invalid to multiply these two matrices. So what do I do? I don't know how to multiply these two three-dimensional vectors? What do I need to do first?
  2. jcsd
  3. Sep 30, 2007 #2


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    Homework Helper

    Have you learned about how to take the dot product between two vectors in component notation? I suspect that's the approach you're expected to take, given the choice of these vectors in three dimensions... (BTW, P = F·v is a better way to write the equation for this sort of problem.)
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