Second year physics homework, thought I was capable and now am simply frustrated

[AloneWeSink]

So I told my sister I could help her with her physics homework, having an old computer engineering degree, and this first problem she sends me has me stumped. If anyone is willing to help this busy and forgetful young man help his sister I would be immensely appreciative. Thank you in advance.

1. Homework Statement [/b]

Determine the Moment of this force about point O.

 

[SammyS]

So I told my sister I could help her with her physics homework, having an old computer engineering degree, and this first problem she sends me has me stumped. If anyone is willing to help this busy and forgetful young man help his sister I would be immensely appreciative. Thank you in advance.

1. Homework Statement [/b]
[ IMG] http://session.masteringengineering.com/problemAsset/1529323/3/Hibbler.ch4.p42.jpg[/PLAIN]
Determine the Moment of this force about point O.

The Moment of F about point O is the same thing as the torque that force F exerts about point O.

It's given by $\displaystyle \ \ \vec{M}_0=\vec{r}\times\vec{F}\,, \$ where $\ \vec{r}\$ is a position vector from point O to the line of action of force $\ \vec{F}\ .$ For example you could take r to be $\ \vec{r}=\vec{OA}\ .$

You will need to construct $\ \vec{r}\$ and $\ \vec{F}\$ from the geometry of the situation as shown in the figure.