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!

Nonstandard integral

  1. Feb 17, 2008 #1
    1. Find the amount of work done by the constant force field [itex] dx + 3dy - dz [/itex] as it moves a particle along the intersection of the planes [itex] x+y+z = 1 [/itex] and [itex] x-2y = -2 [/itex] from where it intersects the [itex] y,z [/itex] plane ([itex] x = 0 [/itex]) to where it intersects the [itex] z,x [/itex] plane ([itex] y = 0 [/itex]).

    So the intersection is [tex] z = 0 [/tex] and [tex] z = 3 [/tex]. Then what would I do?
  2. jcsd
  3. Feb 17, 2008 #2


    User Avatar
    Staff Emeritus
    Science Advisor

    I have absolutely no idea what you mean by "the intersection is z= 0 and z= 3" or how you got that! The intersection of two planes is a line, not two points. You are to integrate along that line.

    If x+ y+ z= 1, then x= 1- y- zo. If x- 2y= -2, then x= 2y- 2 so we have 2y- 2= 1- y- z.
    z= 1- 3y. In other words, the intersection of x+ y+ z= 1 and x- 2y= -2 is given by x= 2t- 2, y= t, z= 1- 3t. That crosses the yz plane when x= 2t- 2= 0 or t= 1. It crosses the xz plane when y= t= 0.

    Integrate dx+ 3dy- dz over that line from t= 1 to t= 0.

    (I also have no idea why you consider that integral "nonstandard". It's about as "standard" as there is!)
  4. Feb 18, 2008 #3
    I sure don't know about this little beast like question my friend.

    It sure is a cancerous question.
    sorry for my bad english

    C to the T to the remBath

    much love
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?