Which of the following choices is NOT a possible formula for impulse?
Take note that $\vec{I}$ = Impulse, $\vec{F}$ = force, and $t$ = time.
$\vec{I} = \vec{F}_{mean}(t_f - t_i)$
$\vec{I} = \vec{F}_{net}\Delta t$
$\vec{I} = (\sum \vec{F})t$
$\vec{I} = \frac{\Delta \vec{F}}{\Delta t}$