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: Volume of Solids of Revolution

  1. Jun 16, 2010 #1
    Find the volume of the solid st,
    1. y=cos x , y= 0 in [0,pi] ; Rotated around x=1




    2. I am slightly confused, I see that the area will double around twice so I can just use the left half of the curve. I am just not sure how to do so.
     
  2. jcsd
  3. Jun 16, 2010 #2

    Mark44

    Staff: Mentor

    Are you sure that you copied this problem correctly. The line x = 1 does not divide the region between y = cosx and y = 0 into two equal halves, so rotating it around the line x = 1 makes a complicated volume of revolution. Could it be that you're supposed to rotate the region around the line y = 1?
     
  4. Jun 16, 2010 #3
    Yes, not 2 equal halves but the rotation around the x=1 axis would cover the right hand side of the curve in rotation and double over so cant we ignore that piece?
     
  5. Jun 16, 2010 #4

    Mark44

    Staff: Mentor

    No, I don't think so. The part of the region under y = cosx on [0, 1] would cover the part on [1, pi/2], so I suppose you could ignore that part. The part of the curve on [pi/2, pi] is below the x-axis. The part above [0, 1] is above the x-axis. This is a very unusual problem.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook