Register to reply

Conservation Laws

by Magister
Tags: conservation, laws
Share this thread:
Magister
#1
Mar28-07, 06:44 AM
P: 83
1. The problem statement, all variables and given/known data

A particle moves in a conservative field of force produced by a mass distribution. In each instance the force generated by a volume element of the distribution is derived from a potential that is proportional to the mass of the volume element and is a function only of the scalar distance from the volume element.
Supose that the mass is uniformly distributed in a circular cylinder of finite length, with axis along the z axis. What are the conserved quantities in the motion of the particle?

2. Relevant equations

The fact that if the space is uniform then the linear momentum is conserved and that if the space is invariant to rotations then the angular momentum is conserved.


3. The attempt at a solution

The linear momentum is not conserved in any direction and the angular momentum is only conserved along the z axis. Am I wrong?

But lets now supose that the cylinder has infinite length. In this case the space is uniform along the z axis and hence the linear momentum along z is also conserved. Am I wrong?

Thanks for your time.
Phys.Org News Partner Science news on Phys.org
Mysterious source of ozone-depleting chemical baffles NASA
Water leads to chemical that gunks up biofuels production
How lizards regenerate their tails: Researchers discover genetic 'recipe'
Dick
#2
Mar28-07, 07:47 AM
Sci Advisor
HW Helper
Thanks
P: 25,228
I think your reasoning is correct.
Magister
#3
Mar28-07, 06:09 PM
P: 83
What about if the mass is in the form of a uniform wire wound in the geometry of an infinite helical solenoid, with axis along the z axis?
The only symmetry in the system is a translation together with a rotation along the z axis. What does that means in terms of conserved quantities?


Register to reply

Related Discussions
Conservation Laws Classical Physics 13
Conservation Laws Special & General Relativity 13
Violation of Conservation Laws Introductory Physics Homework 7
Conservation Laws General Physics 1
I need help with Conservation Laws! Introductory Physics Homework 1