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

1. Feb 6, 2007

### suspenc3

1. The problem statement, all variables and given/known data

See attachment, Im getting everyone of these problems wrong.

2. Relevant 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

3. 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

#### Attached Files:

• ###### car1.JPG
File size:
37.9 KB
Views:
55
Last edited: Feb 6, 2007
2. Feb 6, 2007

anyone????

3. Feb 6, 2007

### teknodude

Well there's a few ways you can do this. The easiest is to take a moment about the y-axis. You have the force in vector form now, so in your diagram you can redraw that force in the x,y,z direction. Then use the right-hand rule to decide which forces produce moments about the y-axis.