Question

i hope this makes sense.

Say that i have x and y axis. then i have an arrow coming out similiar to how you would draw a resultant arrow in physics.

the arrow represents Force=140N

Then say that you have to find the moment about O and the origin is O.

So the first step is to find Fx and Fy.

Then you use M=Fd to solve the problem but you also have to use the right hand rule to figure out the direction for each force and distance.

Say that Fx=4i. I know to find the direction you do rXF. But when i use the right hand rule, after i put my hand in the r direction, do i curl my finger in the F direction or the Fx direction.

also i have solutions to my textbook. Sometimes they say that clockwise is positive and counterclockwise is positive. How do you decide whether each is positive or not. I thought usually, counterclockwise was positive

Answer 1

counterclockwise is positive.

http://en.wikipedia.org/wiki/Right_hand_rule

Answer 2

you didn't answer my other question about which force to use.