- #1

pearss

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## Homework Statement

I have a force in three dimensions such that:

F=600N

Alpha(angle with x axis) = 120

Beta(angle with y axis) = 60

Omega(angle with z axis) = 45

I'm to find the projection of

**F**along the y axis.

## The Attempt at a Solution

I found the force vector for this force by

**F**=F(cos120

**i**+cos60

**j**+cos45

**k**)

**F**=600N(-.5

**i**+.5

**j**+.707

**k**)

**F**= -300

**i**+300

**j**+424.2

**k**

now i know to use a dot product between the force vector and the unit vector of the vector that i'm trying to find a projection onto....but since the vector is the y axis i'm unsure about what to do from here.

I thought that

**u**_OY =

**oy**/magnitude oy

0

**i**+

**j**+0

**k**/ 1 =

**j**

and a dot product between this and my force vector would just give me the y component of that force vector....300.

but i'm pretty sure this is wrong. does anybody have any hints? Thanks much