Page History

This [model|model] is applicable to a [point particle] (or to a [system|system] of objects treated as a [point particle|point particle] located at the system's [center of mass]) when the [external forces|external force] are known or needed.  It is a subclass of the model [Momentum and External Force] defined by the constraint _dm/dt_ = 0.

h5. Learning Objectives

Students will be assumed to understand this model who can:

* State and explain the significance of Newton's Laws of Motion.
* Define [normal force] and describe its relationship to [weight].
* Discriminate between [static|static friction] and [kinetic|kinetic friction] friction.
* Explain the role of the [coefficient of friction] in both the [kinetic|kinetic friction] and [static|static friction] cases.
* Construct a [free body diagram] for an object subject to [contact forces|contact force], [gravity|gravity (near-earth)], [elastic forces|Hooke's Law for elastic interactions], and/or [tension forces|tension].  
* Construct and solve a system of equations describing the dynamics of more than one object that interact with one another.


h4. S.I.M. Structure of the Model

h5. Compatible Systems

A single [point particle|point particle], or a system of constant mass that is treated as a point particle located at the system's center of mass.

h5. Relevant Interactions

[External forces|external force] must be understood sufficiently to draw a [free body diagram] for the system.  [Internal forces|internal force] will always cancel from the equations of Newton's 2nd Law for the system and can be neglected.

h4. Law of Change

h5. Mathematical Representation

{latex}\begin{large} \[ \sum \vec{F}^{\rm ext} = m\vec{a} \]  \end{large} {latex}

{note}As with all vector equations, this Law of Interaction should really be understood as three simultaneous equations:\\

{latex}

As with all vector equations, this Law of Interaction should really be understood as three simultaneous equations:

\begin{large}\[ \sum F^{\rm ext}_{x} = ma_{x}\]
\[ \sum F^{\rm ext}_{y} = ma_{y}\]
\[\sum F^{\rm ext}_{z} = ma_{z}\]\end{large}