# Sun and Purple Planet

Topics: Sun, Orbit, Solar System Pages: 3 (628 words) Published: March 23, 2015
﻿Name _________Brian Bowlan Gravitational Lab Go to http://phet.colorado.edu/simulations/sims.php?sim=My_Solar_System and click on Run Now.

1. Move the slider all the way to accurate, click on the tape measure and the grid. 2. Click the radio button for 4 objects and run the simulation until the purple planet (body 2) has made one complete orbit (one year). 3. After the first orbit (year), turn off the traces (show traces box) and watch another orbit (year) of the purple planet (body 2). Question One:

Is blue moon (body 3) circling the yellow sun (body 1) or the purple planet (body 2)? Explain your answer. The blue moon is circling both the puple plane and the yellow sun. It is circling the purple planet, while the purple planet is circling around the sun. Therefore, it is going around both 4. Increase the mass of the sun (body 1) to 400 and allow the simulation to run for one complete orbit of the purple planet (body 2). 5. Decrease the mass of the sun (body 1) to 175 and allow the simulation to run for one complete orbit of the purple planet (body 2). (~90 seconds) Question Two:

How do the orbits of the planets change when the mass of the sun is increased or decreased? Why? Explain your answer. When the mass of the sun is increased, the gravitational pull is greater. Therefore the orbit is smaller. When the mass of the sun is decreased, the orbit is larger.

Question Three:
Why does the sun (body 1) follow a circular path? How does the path change as its mass changes? Why? Explain your answer. The sun follows a circular path because it is being influenced by the gravitational pull of the planets. When the mass of the sun is closer to the mass of the planet, the circle is larger. This is because the gravitational force increases. 6. Choose the preset for Sun and Planet from the pull-down menu. 7. Complete the data table below by changing the mass as shown and recording the length of the year in seconds, and...