I used to know this, but now it's just confusing me. When you see an object on an incline, you need to break the forces down into components -- But in which direction is the force of gravity before you break it down into components?

[img]http://www.darkvariant.com/dubbs/physics.gif[/img]
Red or Blue?

Fg would be red, blue would be Fg|| or whatever you want to call it.

[quote author=Eibro link=board=36;threadid=5549;start=0#msg47123 date=1078262268]
Fg would be red, blue would be Fg|| or whatever you want to call it.
[/quote]

So if we call the plane the object is on the X axis and the direction of the normal force the Y axis,
G[sub]x[/sub] = Mass*Gravity/sin(theta)
and
G[sub]y[/sub] = Mass*Gravity/cos(theta)

?

[quote author=K link=board=36;threadid=5549;start=0#msg47124 date=1078262635]
[quote author=Eibro link=board=36;threadid=5549;start=0#msg47123 date=1078262268]
Fg would be red, blue would be Fg|| or whatever you want to call it.
[/quote]

So if we call the plane the object is on the X axis and the direction of the normal force the Y axis,
G[sub]x[/sub] = Mass*Gravity/sin(theta)
and
G[sub]y[/sub] = Mass*Gravity/cos(theta)

?

[/quote]Yes, the formulas you found seem correct to me.

The direction of gravity is always down. In fact, philosophically speaking, the physical definition of "down" is the direction of the gravity field. Don't you think?