Momentum

defined as " a measure of how difficult it would be to stop a moving object"

defined as mass times velocity

symbol:   $\overrightarrow{p}$  

unit:  kilogram-meter per second

2nd big conservation law in Physics (after Conservation of Energy)

The total momentum of a system of objects remains constant.

Very useful in observing collisions and explosions.

Impulse defined as Force times time.

A large impulse can happen with a small force - exerted for a long time OR over a short time with a very large force.

Symbol :  $\overrightarrow{J}$  

Unit:  Newton-second

Impulse ALSO equal to CHANGE in momentum

 $\overrightarrow{J\ }\ =\ \ \overrightarrow{F}\ \cdot t\ =\ \Delta\ \overrightarrow{p}\ \$