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: Conservation of Angular Momentum

  1. Apr 23, 2012 #1
    Why is angular momentum conserved about point A? I know that integral(M,A dt) = H,2A - H,1A, where M,A is the moment of all forces about point A, H,2A is the angular momentum about point A after the impact and H,1A is the angular momentum about point A before the impact. If angular momentum was conserved, it would mean that integral(M,O dt) = 0. In the problem, however, there is a weight that is causing a moment about point A. Why is this ignored?
  2. jcsd
  3. Apr 23, 2012 #2

    Doc Al

    User Avatar

    Staff: Mentor

    They are assuming that the collision takes only a very short time--so any effect of gravity can be ignored during the collision. The angular momentum about A immediately before the collision equals the angular momentum about A immediately after the collision.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook