Unit Summary and Assignment 3

Momentum:  a vector quantity, it is the product of the mass and velocity of the an object. It is expressed as the equation

$\overrightarrow{p}=m\overrightarrow{v}$

Impulse: the change in momentum, $∆\overrightarrow{p}$, and the Force acting on an object for time, $\overrightarrow{F}∆t$ as derived from Newton's 2nd Law.

$\overrightarrow{F}∆t=∆\overrightarrow{p}$

Conservation of Momentum: in an isolated system the sum of the momentum before a collision equals the sum of the momentum in the same system after a collision. In other words it is conserved in the x-direction and the y-direction 

$$\begin{gathered} \sum _{}{\overrightarrow{p}}_i=\sum _{}{\overrightarrow{p}}_f \\ \sum _{}{\overrightarrow{p}}_{ix}=\sum _{}{\overrightarrow{p}}_{fx} \\ \sum _{}{\overrightarrow{p}}_{iy}=\sum _{}{\overrightarrow{p}}_{fy} \end{gathered}$$

Perfectly elastic collisions:  a collision that results in the total kinetic energy of the system being conserved.   Perfectly elastic collisions generally occur only at the subatomic level.

Inelastic collision: a collision that involves some loss of kinetic energy, generally as sound or thermal energy.  This is a broad range, and most collisions fall within this class.