# 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.

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#### A.T.

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.

#### A.T.

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.

#### anorlunda

Mentor
Gold Member
I move this thread to Programming and Computer Science

#### Ibix

Science Advisor
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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#### Ibix

Science Advisor
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?

#### Ibix

Science Advisor
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.

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