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: Angular momentum

  1. Dec 10, 2007 #1
    1. The problem statement, all variables and given/known data
    I'm trying to describe the physical phenomena precession using vectors. I need to explain, why a bicycle wheel, which is spinning in the x-y-plane, and only held up in one of the sides, will start do a spin in the x-z-plane.

    2. Relevant equations
    Using Angular Momentum and Torque; explain the phenomena precession.

    3. The attempt at a solution
    I understand that gravity and the position vector together creates a torque. This of course change the angular momentum over time. With a simple spin, the angular momentum points along the x-axis. The torque creates a change in the angular momentum along the z-axis. This results in a total angular momentum, which is the sum of the original and the change of angular momentum. This of course changes things a bit. And I can see, why making the wheel turn, so that it is orthogonal on the angular momentum i a solution. However, I cannot see, why this is the only solution to the problem? Why is this exactly what happens? I mean, the angular momentum is defined as a cross product, so there must an indefinite amount of solutions to problem; so why is it that it is exactly the solution, where the wheel turns that is the one that happens?

    Thanks in advance.
  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted