NTNUJAVA Virtual Physics Laboratory
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Easy Java Simulations (2001- ) => Examples for beginner who want to learn EJS => Topic started by: Fu-Kwun Hwang on June 13, 2010, 01:44:14 pm

Title: Earth Sun And Moon
Post by: Fu-Kwun Hwang on June 13, 2010, 01:44:14 pm
Earth, Sun  and Moon
A particular case of the three-body problem, this is a simulation of three bodies interacting according to the universal gravitational law.
We have taken the data for the Sun, the Earth and the Moon in order to make it more attractive. The difficult part is to set up initial conditions so that the Moon is captured by the Earth in its translation orbit around the Sun.
In the initialization page, we approximate the real initial position for the Sun, the Earth and the Moon, which produces the situation we are familiar with.

1. As an exercise for your students, delete the initialization page (the one with the real situation of the Sun, Earth and Moon) and ask your students to try to reproduce it!
2. Another interesting activity is to pause the simulation, drag the Sun to a different position and play the simulation again to see how this causes the Moon to scape the trajectory.
3. Now that we dragged a body, why not dragging any of the other ones? (Please recall to pause the simulation before dragging any of the bodies, otherwise the simulation may become unstable) 
Author : Francisco Esquembre 

 Date : February 2002