Description
[Model Hierarchy]
Page Contents |
|---|
Assumed Knowledge
Prior Models
Vocabulary
Model Specification
Keys to Applicability
Can be applied to any system for which external forces are known, especially useful for systems where they are absent (momentum conserved for that system) or act only for a short time (Impulse) as in collisions.
System Structure
Internal Constituents: System is composed of Point particles.
Environment: Only external forces need be considered, since internal forces do not change the system's momentum.
Descriptors
Object Variables: Mass for each object (mj), unless momentum is given directly.
State Variables: Velocity (vj) or momentum (pj) for each object inside the system.
Interaction Variables: External forces (Fext,k) or, alternately, impulses may be specified (Jext,k). They may act on any or all particle(s) in the system.
Laws of Interaction
\begin
[ \frac{d\vec
_{\rm system}}
= \:\sum_
^{N_{F}} \vec
_
]\end
where the system momentum is the vector sum of the constituent momenta:
\begin
[ \vec
_
= \sum_
^
\vec
^
]\end
where N is the number of system constituents. The integral form involves
Impulse:
\begin
[ \vec
_
= \int \vec
_
\:dt ]\end
Laws of Change
\begin
[ \vec
_
= \vec
_
+ \sum_
^{N_{F}} \vec
_
]\end
Relevant Examples
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RELATE wiki by David E. Pritchard is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License |
