# Power Question

## Homework Statement

An object moves with a velocity of [4 m/s,-1 m/s, 3 m/s] and is acted on by a force of [-5 N, 0, +5 N]. What is the power of the energy transfer in this interaction?

a. -35 W
b. -5 W
c. 0
d. +5 W
e. +35 W

p = Fv

## The Attempt at a Solution

Okay, so I'm trying to find p, and I'm given Fv, and I know that p = Fv. The problem is that it's invalid to multiply these two matrices. So what do I do? I don't know how to multiply these two three-dimensional vectors? What do I need to do first?

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Homework Helper

## Homework Statement

An object moves with a velocity of [4 m/s,-1 m/s, 3 m/s] and is acted on by a force of [-5 N, 0, +5 N]. What is the power of the energy transfer in this interaction?

a. -35 W
b. -5 W
c. 0
d. +5 W
e. +35 W

p = Fv

## The Attempt at a Solution

Okay, so I'm trying to find p, and I'm given Fv, and I know that p = Fv. The problem is that it's invalid to multiply these two matrices. So what do I do? I don't know how to multiply these two three-dimensional vectors? What do I need to do first?
Have you learned about how to take the dot product between two vectors in component notation? I suspect that's the approach you're expected to take, given the choice of these vectors in three dimensions... (BTW, P = F·v is a better way to write the equation for this sort of problem.)