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!

Rotating coordinate axes

  1. Feb 15, 2012 #1
    1. The problem statement, all variables and given/known data

    Screenshot2012-02-15at23607AM.png

    17. xy = 2

    Screenshot2012-02-15at23611AM.png

    3. The attempt at a solution

    Do you see that step where they do the following:

    √2/2 - √2/2 = my answer is 0

    and they multiply that to

    √2/2 + √2/2 = my answer is √2

    So to me the answer is 0 * √2 = 0, but the book shows that that calculation = 2, then they set x over 2 and y over 2, don't understand why.

    I don't understand what the book is doing. I understand everything else except that one part.
     
    Last edited: Feb 15, 2012
  2. jcsd
  3. Feb 15, 2012 #2

    tiny-tim

    User Avatar
    Science Advisor
    Homework Helper

    hi bobsmith76! :smile:
    the answer to what? :confused:
     
  4. Feb 15, 2012 #3
    see revision
     
  5. Feb 15, 2012 #4

    tiny-tim

    User Avatar
    Science Advisor
    Homework Helper

    do you mean the LHS of the equation at the beginning of the last line? :confused:

    then you're ignoring the x' and y'

    that LHS multiplies out to 1/2 x'2 - 1/2 y'2, which you can see is the LHS of the next equation

    (and the RHS of both equations stays as 2)
     
  6. Feb 15, 2012 #5
    are you saying they square √2/2 - √2/2? if they do that is still zero. I don't know what you mean by I'm ignoring x'. What x' am i ignoring.
     
  7. Feb 15, 2012 #6

    tiny-tim

    User Avatar
    Science Advisor
    Homework Helper

    they don't have √2/2 - √2/2 !

    are we looking at the same question? :confused:

    all i'm seeing is something similar with x' and y'
     
  8. Feb 15, 2012 #7

    HallsofIvy

    User Avatar
    Staff Emeritus
    Science Advisor

    They are NOT dealing with [itex]\sqrt{2}/2- \sqrt{2}/2[/itex], they are dealing with [itex](\sqrt{2}/2)x'- (\sqrt{2}/2)y'[/itex].
     
  9. Feb 15, 2012 #8
    ok, thanks. I misread what I was reading I thought it was

    (√2/2x' - √2/2x')(√2/2y' + √2/2y')
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Rotating coordinate axes
  1. Rotation of axes (Replies: 3)

  2. Rotation of axes (Replies: 2)

Loading...