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!

Writing equations in cylindrical coordinates (need work checked again please)

  1. Sep 9, 2008 #1
    Could someone tell me what I'm doing wrong? thanks!!

    1. The problem statement, all variables and given/known data

    Write the equation is cylindrical coordinates

    7x2 + 7y2 = 2y

    r = ? (has to be in the r = ? format)

    2. Relevant equations

    r2 = x2 +y2
    x = rcos(θ)
    y = rsin(θ)

    3. The attempt at a solution

    7x2 + 7y2 = 2y

    7(x2 + y2) = 2y

    7(r2 = 2rsin(θ)

    r2 = (2rsin(θ))/7

    r = sqrt((2rsin(θ))/7)
     
  2. jcsd
  3. Sep 9, 2008 #2

    HallsofIvy

    User Avatar
    Staff Emeritus
    Science Advisor

    I think it would be better to leave it as [itex]r^2= (2/7) sin(\theta)[/itex] rather than taking the square root, but, yes, that is correct.
     
  4. Sep 9, 2008 #3
    its an online submission that has r = "enter here" , but i keep getting that its a wrong answer, is there any other way that this could be written?
     
  5. Sep 9, 2008 #4

    Defennder

    User Avatar
    Homework Helper

    Note that you forgot to cancel out r on both sides of the equation. Don't express r in terms of r in the final answer.
     
  6. Sep 10, 2008 #5
    Anybody have any idea about tramsforming the momentum equation into 2-D cylindrical co-ordinates...i've already derived the momentum equation from first principle but have difficulty with the transformation to cylindrical co-ordinates
     
  7. Sep 11, 2008 #6

    Defennder

    User Avatar
    Homework Helper

    Hi, if you have a separate question you should post it in a new thread so that others can aid you. Sometimes people don't bother reading through a thread which already has several replies.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Writing equations in cylindrical coordinates (need work checked again please)
Loading...