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Location on a circle at time t. 
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#1
Aug608, 04:35 PM

P: 4

Hi all. I'm doing a little program for my own fun and I'm having troubles with the physics. I need to be able to calculate where an object is on a circle after an amount of time has passed. I know the radius (R) of the circle, the starting x (Sx) and y (Sy) positions, and the velocity (v). I'd like to be able to generated the finishing x (Fx) and y (Fy) positions. The velocity and radius are constant for each object, but I have several objects rotating around a central point. It's similar to planets orbiting the sun, but I don't need to have any gravitational interaction between the objects. I also know the mass of the objects (m) if I need that for calculating.
Can anyone give me a formula or set of formulas to solve for Fx,Fy? Thanks! 


#2
Aug608, 08:53 PM

P: 295

In terms of the variables given it should be:
[tex] \begin{align*} F_x &= S_x\cos(vt/R)  S_y\sin(vt/R) \\ F_y &= S_x\sin(vt/R) + S_y\cos(vt/R) \end{align*} [/tex] 


#3
Aug708, 10:00 AM

P: 4

That's what I was looking for. Thanks Peeter.



#4
Aug808, 03:43 PM

P: 4

Location on a circle at time t.
I seem to be having problems converting the formulas into my code. Here's the code I've created:
Thanks, NCGrimbo 


#5
Aug808, 04:08 PM

P: 295

Yes, those points were relative to the center at the origin.
[tex] \begin{align*} F_x &= C_x + (S_xC_x)\cos(vt/R)  (S_yC_y)\sin(vt/R) \\ F_y &= C_y + (S_xC_x)\sin(vt/R) + (S_yC_y)\cos(vt/R) \end{align*} [/tex] 


#6
Aug808, 04:49 PM

P: 4




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