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!

Mass of a surface

  1. Apr 11, 2009 #1
    1. The problem statement, all variables and given/known data
    If the mass per unit area of a surface is given by rho = x*y, find the mass
    double integral over S of x*y dS if S is the part of the cylinder x^2 + z^2 = 9 which is in the first octant and contained within the cylinder x^2 + y^2 = 4.


    2. Relevant equations
    Above.


    3. The attempt at a solution
    I can visualize what the shape looks like, but I'm not sure how to define the bounds of integration based on the shape described.
     
  2. jcsd
  3. Apr 11, 2009 #2
    does anyone have any ideas? help would be greatly appreciated.
     
  4. Apr 13, 2009 #3
    Make sure you're visualizing the shape from a useful viewpoint. I suggest looking "from above." In other words, draw the xy-plane as usual on your paper, position your eye directly above the origin, and imagine the z-axis pointing straight out at your eye. Shade the region in the xy-plane that is covered by the surface.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook