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