# Stupid Power Question

1. Jan 7, 2013

### Mandelbroth

Is power given by $\vec{F} \cdot \vec{v}$, or just $Fv$?

I'm thinking it can be both if the velocity and force vectors are parallel, but I'm not sure...

2. Jan 7, 2013

### HallsofIvy

Staff Emeritus
If vector $\vec{F}$ happens to be in the same direction as $\vec{v}$ then $\vec{F}\cdot\vec{v}= |\vec{F}||\vec{v}|$ which is what I think you mean by "Fv". In general, of course, they are not in the same direction and you must use $\vec{F}\cdot\vec{v}$.