1. Limited time only! Sign up for a free 30min personal 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!

Homework Help: Dot product

  1. Apr 14, 2010 #1
    1. The problem statement, all variables and given/known data

    what is the dot product of [tex]G{\bullet}A[/tex] where A = [tex]\left(\frac{a_3}{l}-\frac{{a_1}}{h}\right)[/tex] and G = [tex]2{\pi}h{\frac{{a_2}}x{{a_3}}}{{a_1}{\bullet}{{a_2}}x{{a_3}}}[/tex]

    2. Relevant equations




    3. The attempt at a solution

    The answer is zero and ive got the worked solution infront of me, i just done see where the [tex]\frac{{{a_3}}}{l}[/tex] goes, the dot product of a vector with itself is 1 isnt it? but then where does the denominator go? and what about the denominator of G?
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Apr 14, 2010 #2
    sorry that first bit should say:

    G = [tex]2{\pi}h{\frac{{a_2}x{a_3}}{{a_1}{\bullet}{a_2}x{a_3}}[/tex]
     
  4. Apr 14, 2010 #3

    Mark44

    Staff: Mentor

    I replaced your formula for G by what you had in your 2nd post.
    No, the dot product of a vector is not 1 in general. u [itex]\cdot[/itex] v = |u| |v| cos([itex]\theta[\itex]).

    Speaking of vectors, which are the vectors in your problem?
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook