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!

Conservation of Angular Momentum and Vectors

  1. Mar 11, 2014 #1
    Hi there,

    I'll come straight out with this, I'm really struggling to understand the conservation of angular momentum.

    A common example involves someone sitting on a rotating chair holding a rotating wheel. If the wheel is held so that the axis of rotation is vertical then the person rotates in the opposite direction.

    The total angular momentum is conserved by adding together the momentum of the two bodies.

    Does this mean that when the wheel is turned 90 degrees then it will spin faster since the person on the chair is no longer rotating? The wheel would have to spin faster to conserve angular momentum since there is now only one body rotating right? If this is wrong can someone help to explain please?

    Also I don't understand what it means to say the vector of angular momentum is perpendicular to the plane of rotation. Does that mean there is a force in this direction? If not then why not since momentum includes a mass and velocity?

    Hope that makes sense.

    Many thanks
  2. jcsd
  3. Mar 11, 2014 #2


    User Avatar
    Science Advisor
    Gold Member

    Try this: https://www.khanacademy.org/science/physics/torque-angular-momentum/torque-tutorial/v/conservation-of-angular-momemtum [Broken]

    Or this: http://www.triumphofmind.net/2011/07/angular-momentum-is-easy-or-physics-of.html [Broken]
    Last edited by a moderator: May 6, 2017
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook