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Homework Help: The product of a vector and the length of a polar coordinate

  1. Feb 2, 2014 #1
    1. The problem statement, all variables and given/known data
    So I am not sure how to multiply these two (A*R^2) together.

    2. Relevant equations
    A=( x^2 + y^2 + z^2 ) (xe + y e + z e )
    Where x represents the three vector compones

    I also have R^2=x^2+y^2+z^2

    3. The attempt at a solution

    Is the product of A (x^3e + y^3 e + z^3 e )? If so why is that? I would think because of some vector rule I am not sure of.
  2. jcsd
  3. Feb 2, 2014 #2


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    Gold Member

    You haven't told us what R is. Also, (xe + y e + z e ) is strange notation. Is e the base of natural logarithms? Or is that supposed to represent a vector ##\langle x,y,z\rangle## and is that ##\vec R##? Is ##R^2## supposed to represent ##\vec R \cdot \vec R##? It would help greatly if you would define your terms and use standard notation.
  4. Feb 2, 2014 #3
    R is just (x^2+y^2+z^2)^1/2 and it isn't a vector.

    Let me rewrite A
    A=( x^2 + y^2 + z^2 ) (x[itex]\hat{x}[/itex] + y[itex]\hat{y}[/itex] + z[itex]\hat{z}[/itex] )
  5. Feb 2, 2014 #4


    Staff: Mentor

    x2 + y2 + z2 is just a scalar. What happens when you multiply a vector by a scalar?

    Also, are ##\hat{x}##, ##\hat{y}##, and ##\hat{z}## some random unit vectors? If they are unit vectors in the directions of the x, y, and z axes, they are usually written i, j, and k.
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