# Simulating the Three Body Problem

Jesperchristiansen
Hello.

I want to simulate the Circular Restricted Three Body Problem in excel, however I don't know how to get started, even though I have the equations of motion.
The Planar, Circular Restricted Three Body Problem assumes that one body, m3, is neglebtaly small, and the two other bodies move around a common center of mass.

## Answers and Replies

Science Advisor
I want to simulate the Circular Restricted Three Body Problem in excel, however I don't know how to get started, even though I have the equations of motion.
So you need help with Excel?

Jesperchristiansen
Yes, I’ve successfully created a two body simulation in Excel. However, I don’t know how to simulate a planer three body problem, even though it should be quite easy.

Science Advisor
Yes, I’ve successfully created a two body simulation in Excel. However, I don’t know how to simulate a planer three body problem, even though it should be quite easy.
Then you should ask in the programming sub forum, as this is not really a question about physics.

Staff Emeritus
I move this thread to Programming and Computer Science

Science Advisor
2022 Award
So you've got two bodies that are only influenced by each other (i.e. a two-body problem that you say you've already solved) and a third whose equations of motion depend on its position and velocity and the positions of the first two. Where's the problem?

Jesperchristiansen
So you've got two bodies that are only influenced by each other (i.e. a two-body problem that you say you've already solved) and a third whose equations of motion depend on its position and velocity and the positions of the first two. Where's the problem?

I don't know how to insert the equation of motion of the third body in excel, since it includes vectorrelations as shown in this website: http://www.geom.uiuc.edu/~megraw/MATH1/math1.html

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Science Advisor
2022 Award
None of those quantities are vectors in the form written. You could re-express the equations as a single vector equation instead of two equations in terms of components if you wanted.

Jesperchristiansen
Thanks a lot. How could I do that?

Science Advisor
2022 Award
I'm confused. You've got equations in a non-vectorial format. Presumably you've got some kind of differential equation solver going to have been able to solve the two-body problem. I'm not sure I understand what your difficulties are. Why would you need the equations in a vectorial form? I'm not aware of any way to make Excel handle them, unless you've gone pretty deep into VBA.