Motion along a three-dimensional plane

[leofil]

Hi, I am working on an example that demonstrates Newtons laws in 3-dimensions (this is NOT homework). In my example I focus on incline (frictionless) motion, which can be represented as below in 2-dimensions.

http://imageshack.us/scaled/landing/855/212pxfreebodysvg.png


From Newtons second law (with proper choice of coordinate system) i get:
F_y:= 0 = N - mg cos(alpha)
F_x:= m a_x = f - mg sin(theta)
which then gives me N and a_x.

Can anybody help me with deriving a similar set of equations for a 3-dimensional system (xyz-system).

 

[Vanadium 50]

For three dimensions you can always find a two-dimensional slice.