Go http://phet.colorado.edu/simulations/sims.php?sim=My_Solar_System and click on Run Now.
After the simulation loads click Start.
Describe what you see in this simple sun-planet system.
The planet is rapidly rotating around the sun, while the sun is slowly revolving around its own centralized location.
Specifically, what happens to the central object (the Sun)?
It slowly revolves around its own central point.
Can you explain why the central object moves?
I would say that it is from gravitational pull. Everything has its own gravity. Everything exerts a pulling force on everything else. Thus, the sun exerts a force within the planet causing it to rotate.
Does the planet orbit in a perfect circle? Is the sun at the center? Yes, the planet orbits in a perfect circle around the sun. No, the sun is not at the center. It is offset to the right of the center of the circle.
Click Stop and then select 3 bodies. Then Start
Sketch a complete cycle (orbit)
Watch the ‘funny’ object closely
What is it doing? Describe and explain.
The newly added body appears to be rotating completely around the other body. It has an infinite pattern of doing this.
Could this be the Earth/Moon/Sun system? (Try un-checking Show Traces.) This could in fact be the Earth/Moon/Sun system. It seems to have the same physical characteristics, as well as actions.
Is there anything you are uncomfortable with in the simulation? Explain. Yes, it made me really dizzy watching it. If I just watched the “funny” object, I would lose focus of everything else.
Can you explain the difference in the moon’s path when it is on the right
side of the Sun compared to on the left side? (Turn Traces back on.) As it gets closer to the right side of the sun, the moon seems to speed up. As it moves farther away from the sun, it slows back down. This is due to both gravitational pull and orbital velocity.
Click Stop and...
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