Gravitation Phet Simulations Physics 2010

Name :                                                                         Gravitation Lab            

Objective:

• The objective of this experiment is to simulate Earth/Moon/Sun system

Procedure with data:

Go http://phet.colorado.edu/simulations/sims.php?sim=My_Solar_System

and click on Run Now.

I           After the simulation loads click Start.

                        Describe what you see in this simple sun-planet system.

                                    Specifically, what happens to the central object (the Sun)?

                                    Can you explain why the central object moves?

                                    HINT: Is gravitational attraction only the sun pulling on the planet?

                                    Does the planet orbit in a perfect circle? Is the sun at the center?

II       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.

                                    Could this be the Earth/Moon/Sun system? (Try un-checking Show Traces.)

                                    Is there anything you are uncomfortable with in the simulation? Explain.

                                    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.)

III        Click Stop and then select 4 bodies. Then Start

                        Describe what is happening to the inner planet, why.

IV        Click Stop and then select 2 bodies again.

                        Change the mass of the ‘planet’ to 100 units and then Start.

                                    Explain how the motion is different from Part I.

                                               Ever hear of a binary star?

                        Repeat with both bodies at 200 units of mass.

V         Click Stop and then select 3 bodies again.

                        Change the masses of bodies 2 and 3 to 5 units each and Start.

                                    Watch for several orbits and explain what’s happening.

VI        Continue to explore on your own by changing variables—“what if?”.

                                    What if two planets with same weight at closer distance travels at the same speed.