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 a sphere

  1. Jun 23, 2013 #1
    1. The problem statement, all variables and given/known data

    Show that the volume of a sphere of radius r is

    V = (4/3)πr^2

    2. Relevant equations

    calculus, integration

    3. The attempt at a solution

    I have the solution in the book but it's confusing me, I'll attach a picture.

    2m7zp88.jpg

    So I get lost where it starts talking about a cross-sectional area all of a sudden multiplying by ∏. What's going on here?!
     
  2. jcsd
  3. Jun 23, 2013 #2

    D H

    User Avatar
    Staff Emeritus
    Science Advisor

    What's the area of a circle of radius r? What if the radius is y instead of r?
     
  4. Jun 24, 2013 #3

    Mark44

    Staff: Mentor

    Probably a typo - the volume is (4/3)##\pi r^3##.

    The book is using disks that are oriented vertically (the x-axis intersects each disk perpendicularly). The volume of such a disk is its area times its thickness, dx.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Loading...