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{
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}{composition-setup} {table:rules=cols|cellpadding=8|cellspacing=0|border=1|frame=void} {tr:valign=top} {td} h4. Introduction to the Model h5. Description and Assumptions {excerpt:hidden=true}*[*System*|system]**:* Any. --- *[*Interactions*|interaction]**:* Any. --- *Note:* Linear [momentum|momentum] evolves separately from [angular momentum|angular momentum about a single axis], so all system constituents are treated as [point particles|point particle] in this [model|model].{excerpt} This [model|model] is generally applicable (assuming knowledge of the external [forces|force] and [system|system] [constituents|system constituent]). The [model|model] is especially useful when describing the [momentum|momentum] of [systems|system] where [external forces|external force] are absent ([system|system] [momentum|momentum] will be constant) or estimating the [force|force] in a process that occurs in a very short time interval such as collisions ([impulse|impulse] will be easier to determine than [force|force]). h5. Learning Objectives Students will be assumed to understand this model who can: * Define the momentum of a [point particle]. * Define [impulse] in terms of [momentum] or in terms of [force]. * Give an expression for the time-average [force] on a [system] in terms of its [momentum]. * Calculate the net [external force] on a [system] containing several objects. * Describe the conditions required for the [momentum] of a [system] to be [conserved]. * Describe the [system] that must be considered and the assumptions that lead to approximate conservation of momentum in a collision. h5. Relevant Definitions \\ {latex}
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Introduction to the Model

Description and Assumptions

Excerpt
hiddentrue

System: Any. — Interactions: Any. — Note: Linear momentum evolves separately from angular momentum, so all system constituents are treated as point particles in this model.


This model is generally applicable (assuming knowledge of the external forces and system constituents). The model is especially useful when describing the momentum of systems where external forces are absent (system momentum will be constant) or estimating the force in a process that occurs in a very short time interval such as collisions (impulse will be easier to determine than force).

Learning Objectives

Students will be assumed to understand this model who can:

Relevant Definitions


Latex
\begin{large}\[ \vec{p} = m\vec{v}\]\end{large}
{latex} h4.

S.I.M.

Structure

of

the

Model

h5.

Compatible
Systems

The

system

must

be

effectively

composed

of

[

point

particles

|point particle]

,

though

rigid

bodies

may

be

treated

as

point

particles

with

positions

specified

by

the

center

of

mass

positions

of

the

rigid

body

when

this

model

is

used.

h5.

Relevant
Interactions

Only

[

external

forces

|external force]

need

be

considered,

since

[

internal

forces

|internal force]

do

not

change

the

system's

momentum.

h4.

Laws

of

Change

h5.

Mathematical
Representation
{section} {column} h6. Differential Form \\ {latex}
Section
Column
Differential Form


Latex
\begin{large}\[ 
\sum_{
\
rm system}\
frac{d\vec{p}}{dt} = \sum
_{\rm
 
external}
\vec{F}^{\rm ext}\]\end{large}
{latex} {column} {column:width=40px} {column} {column} h6. Integral Form \\ {latex}
Column
width40px

Column
Integral Form


Latex
\begin{large}\[ \
sum_{\rm system}\
vec{p}_{f} =
\sum_{\rm
 
system}
\vec{p}_{i} + \sum
_{\rm external}
 \vec{J}
= \sum_
^{\rm 
system}
ext}_{fi} = \vec{p}_{i} + \int_{t_{i}}^{t_{f}} \sum
_{\rm external}
 \vec{F}^{\rm ext}\:dt  \]
\end{large}
{latex} {column} {section} h5. Diagrammatic Representations * [
Diagrammatic Representations
] * [
diagram] h4. Relevant Examples h6. {

Relevant Examples

Toggle Cloak
:
id
=
const
}
Examples
Involving
Constant
Momentum
{
Cloak
:
id
=const} {contentbylabel:constant_momentum|showSpace=false|showLabels=true|excerpt=true|maxResults=50} {cloak} h6. {toggle-cloak:id=imp} Examples Involving Impulse {cloak:id=imp} {contentbylabel:impulse|showSpace=false|showLabels=true|excerpt=true|maxResults=50} {cloak} h6. {toggle-cloak:id=oned} Examples Involving 1-D Collisions {cloak:id=oned} {contentbylabel:1d_collision|showSpace=false|showLabels=true|excerpt=true|maxResults=50} {cloak} h6. {toggle-cloak:id=twod} Examples Involving 2-D Collisions {cloak:id=twod} {contentbylabel:2d_collision|showSpace=false|showLabels=true|excerpt=true|maxResults=50} {cloak} h6. {toggle-cloak:id=elas} Examples Involving Elastic Collisions {cloak:id=elas} {contentbylabel:elastic_collision|showSpace=false|showLabels=true|excerpt=true|maxResults=50} {cloak} h6. {toggle-cloak:id=inel} Examples Involving Totally Inelastic Collisions {cloak:id=inel} {contentbylabel:totally_inelastic|showSpace=false|showLabels=true|excerpt=true|maxResults=50} {cloak} h6. {toggle-cloak:id=flux} Examples Involving Continuous Momentum Flux {cloak:id=flux} {contentbylabel:momentum_force|showSpace=false|showLabels=true|excerpt=true|maxResults=50} {cloak} h6. {toggle-cloak:id=all} All Examples Using this Model {cloak:id=all} {contentbylabel:constant_momentum,momentum_force,impulse|showSpace=false|showLabels=true|excerpt=true|operator=OR|maxResults=50} {cloak} ---- {search-box} \\ {td} {td:width=235px} [!billiards.jpg|width=235px, alt="Click on the image to learn a handy rule of thumb for pool shots."!|Cue the Right-Angle Bracket]\\ !skaters.jpg|width=235px!\\ !shuttle.jpg! Photos courtesy: * [Wikimedia Commons|http://commons.wikimedia.org] by user [No-w-ay|http://commons.wikimedia.org/wiki/User:No-w-ay] in collaboration with H. Caps * [Wikimedia Commons|http://commons.wikimedia.org] by user [Uwe Langer|http://commons.wikimedia.org/wiki/User:Uwe_Langer] * [NASA Johnson Space Center (NASA-JSC)|http://images.jsc.nasa.gov] {td} {tr} {table} \\
const
falsetruetrue50constant_momentum
Toggle Cloak
idimp
Examples Involving Impulse
Cloak
idimp
falsetruetrue50impulse
Toggle Cloak
idoned
Examples Involving 1-D Collisions
Cloak
idoned
falsetruetrue501d_collision
Toggle Cloak
idtwod
Examples Involving 2-D Collisions
Cloak
idtwod
falsetruetrue502d_collision
Toggle Cloak
idelas
Examples Involving Elastic Collisions
Cloak
idelas
falsetruetrue50elastic_collision
Toggle Cloak
idinel
Examples Involving Totally Inelastic Collisions
Cloak
idinel
falsetruetrue50totally_inelastic
Toggle Cloak
idflux
Examples Involving Continuous Momentum Flux
Cloak
idflux
falsetruetrue50momentum_force
Toggle Cloak
idall
All Examples Using this Model
Cloak
idall
falsetruetrueOR50constant_momentum,momentum_force,impulse

Search Box


Table Cell (td)
width235px

Click on the image to learn a handy rule of thumb for pool shots.Image Added

Image Added

Image Added
Photos courtesy:


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