Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Gravitational Field Strength due to a Uniform Rod

  1. Jun 16, 2014 #1
    I am trying to learn Physics an dI am reading a booK about classical mechanics.I a stuck somewhere in there If you know a gravitational force to a uniform rod I saw there a x and dx Why we need them ?

  2. jcsd
  3. Jun 16, 2014 #2


    User Avatar
    Science Advisor
    Gold Member

    You need to integrate the gravitational effects of infinitesimal lengths along the rod to get the total for the rod.
  4. Jun 16, 2014 #3


    User Avatar

    Staff: Mentor

    That's part of the notation of calculus. If you'd tell us what the book was, we'd be certain... But chances are that they're dividing the rod into slices and using dx as the thickness of each slice and x as the position of the slice along the rod. Then the contribution of each slice can be approximated from Newton's inverse-square law and calculus provides the mathematical tools to add all the contributions up as the number of slices approaches infinity and the thickness of each slice approaches zero - and a proof that this process yields an exact answer.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted