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Feature
REALScience
Basic Planetary Motion
Issue: 4.5 (May/June 2006)
Author: JC Cruz
Article Description: No description available.
Article Length (in bytes): 19,595
Starting Page Number: 21
RBD Number: 4509
Resource File(s):
4509.sit Updated: Monday, May 15, 2006 at 4:51 PM
Related Web Link(s):
http://nssdc.gsfc.nasa.gov/planetary/factsheet
http://en.wikipedia.org/wiki/Planetary_orbit
http://en.wikipedia.org/wiki/Two-body_problem
http://en.wikipedia.org/wiki/N-body_problem
http://en.wikipedia.org/wiki/Gravitational_constant
http://www.nineplanets.org
http://en.wikipedia.org/wiki/Ellipse
Known Limitations: None
Excerpt of article text...
In my previous article, I covered the basic physics behind harmonic motion. I also introduced a new ODE algorithm, known as the Runge-Kutta Fourth Order (RK4), to replace the simple Euler's Method. I have shown the basic mathematics behind this new algorithm as well as some pertinent issues. I have also demonstrated how to use RK4 to simulate a prime example of harmonic motion, the simple pendulum.
Today, I will be discussing the basic physics behind planetary motion. I will cover some of the issues involved when simulating a planetary system. Later on, I will demonstrate how to use a vectorial version of RK4 to simulate a three-body system.
So pay attention, bright readers. This is going to be an interesting ride.
Basic Concepts
Astronomical Units of Measure
One notable aspect about planetary motion is that all data being processed are large in orders of magnitude. Masses are often in the order of at least a billion kilograms. The same is also true for other quantities such as velocities and positions.
...End of Excerpt. Please purchase the magazine to read the full article.
Article copyrighted by REALbasic Developer magazine. All rights reserved.
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