# How do I show the 100N force is cartesian form?

## Homework Statement

See attachment, Im getting everyone of these problems wrong.

## Homework Equations

$$M_y = u_y(r_y X F)$$

Where u=unit vector defining the direction of y axis
r=distance from y axis to any point on the line of action of F
F=acting force

## The Attempt at a Solution

I think im going wrong right from the beginning, how do I show the 100N force is cartesian form? What im doing is :

A=1.2i+0j+0k
B=0.6i+0.6j+1.2k

$$AB =\frac{ -0.6i+0.6j+1.2k}{\sqrt{0.6^2+0.6^2+1.2^2}}$$

$$F_{AB} = (100N)\frac{ -0.6i+0.6j+1.2k}{\sqrt{0.6^2+0.6^2+1.2^2}}$$

Im not going to bother to post the rest since im pretty sure this isnt how to do this.

Thanks

#### Attachments

• car1.JPG
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