1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Quick cross product question

  1. Apr 9, 2012 #1
    this is a general question - the thing i'm working on if what i am asking makes sense - i am currently only looking for a confirmation on what i think is right

    this is a vector product question:

    if i have:

    (A/c x cB)

    can i look at that as:

    (1/c*c)(A x B)

    which comes to

    A x B

    the question is - can i take the constant, c, out in the way i am showing? i ask this as i cannot find an identity that confirms this.
     
  2. jcsd
  3. Apr 9, 2012 #2

    Andrew Mason

    User Avatar
    Science Advisor
    Homework Helper

    Just use the definition of cross product of two vectors X and Y, which is a vector which has magnitude |X||Y|sinθ in a direction given by the right hand rule perpendicular to the plane of X and Y. What are the magnitudes of [itex]1/c(\vec{A})[/itex] and [itex]c\vec{B}[/itex]?

    AM
     
  4. Apr 9, 2012 #3
    A/c X cB by definition is the vector such that
    < A/c X cB, n > = Det [ A/c , cB, n ] for all n. By the properties of the determinant,
    Det [ A/c , cB, n ] = 1/c*c Det[A,B,n] = Det[A,B,n] = < A X B, n > for all n. Finally,
    < A/c X cB, n > - < A X B, n > = 0 for all n, so A X B = A/c X cB.


    ( < > is the inner product, or just the dot product in this case )
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Quick cross product question
  1. Cross product Question (Replies: 4)

Loading...