Force Diagrams

[jfaure]

just wondering, do you include the sine and cosine forces acting on an object, when asked to draw in all the forces?? (obviously for inclined plane questions)

[vce08]

No i don't think so.
They are not forces per se. They are resolved forces.

[shinny]

Don't write them down because you'll probably lose a mark. What I tend to do is draw dotted lines where they are though so you don't forget to include them later.

[jfaure]

thanks alot

[shinny]

Basically in a force diagram, only draw the ORIGINAL FORCES. Don't resolve anything, don't write for friction (because friction isn't always at its maximum), and the only ones I'd assign numerical values ever are the weight force and external forces where they've given you the value. Define all variables, even for stuff like N just to prevent examiners having any reason to take marks off you. Also draw them all coming from the same point, and if theres two in the same direction, just draw it slightly higher; don't overlap the arrows.

[Quickclaw]

I'd say draw another diagram somewhere else for your own interpretation.