[F8] planetary motion

[18Scribbler01]

I've been trying to make a flashmovie that shows how a planet moves around its star according to some phisical laws. I've looked up some tutorials on this sort of thing but they're not really handeling it in a way i want to. I want do be able to use actual (scaled) values for distances and masses and I also want to use Newton's gravitylaw.

To use the gravity law i've set the planet's distance "r" to sqrt(_x^2 + _y^2)
I've set it's angular speed "w" to v/r where i only defined "v" as sqrt(Gm/r)
Then I defined its components as: vy=sin(p)*v and vx=cos(p)*v.

My problem is that it needs to calculate the planets position as wel as its speed ervery time. I kinda lost the code so i don't know exactlywhat i did so far.

To start things off, is it actually possible to use exactly these formulas?
And how should i start?

[wattsup]

here is a link that has the use of physics maybe it might help you. ( not sure )

http://www.krazydad.com/bestiary/

[18Scribbler01]

Thanks, thats an interesting site. However i think it's a bot too difficult for me to get the right stuff out of these codes. He uses some external files and certain codes I haven't seen yet.

Eventually I can probebly understand quite a bit of these codes but for now its just too much work to figure it all out. Maybe someone can take some smaller steps toward my goal? I have to start with only two objects that's all, i'll work my way up from there.

[Eager Beaver]

Hi! Please see the FLA (F8) taken out from my library and attached to this post.
Hope this is what you wanted!

[18Scribbler01]

That looks really nice, but its not what i mean. This seems to be a mathmatical function descibing circular motion. I want to use newton's law of gravity F = -(G*m1*m2)/(r^2) and the centripital force F = m* v^2/r. So that i get a motion that depends on how far the planet is from its star and how fast its moving around it. If for example you were to give it a speed too small it would crash into the planet's star or too great it would fly off. My goal is to make sort of an educational movie on planetary motion in which you can mess around with weight, velocity and distance.

[Eager Beaver]

I know,
m= mass
r=radius
v=velocity
but what is G?

[18Scribbler01]

Gravitational constant: 6.76*10^-11 N.m^2.kg^-2