Gravitation

(Another in a series of experimental internet delivered activities)

Click here to go to James P. Riser's home pages.

Required software:

Gravitation 5.0b1 by Jeff Rommereide (Macintosh only) can be downloaded from the internet.

About the software:

Gravitation is a simulation program that will allow the user to experiment with hypothetical systems that might be found in space. Masses, distances, directions of movement, velocities, and numbers of objects may all be varied and visually observed for interaction.

Note: After starting the program, be certain to check out the Help and Info... under the Apple Menu to learn about using the software. To examine or create the settings for a system, select Solar System Editor from the Edit Menu.

Purpose of this activity:

This activity was designed so that my students (by utilizing a powerful simulation program to design and experiment) could better understand and appreciate factors affecting a system.

Necessary background information:

Mass is a measurement of the amount of matter in an object.
The more mass in an object, the stronger its gravitational field.
Gravitational attraction between two objects increases as they get closer and decreases as they get farther apart.
The orbiting velocity of an object can equal or even overcome the gravitational attraction between two objects.

Your Assignment:

- Observation phase -

Select at least six of the example files under File/Open.
Run each example separately and examine the data (under Edit/Solar System Editor) for each example.
Write a full description of what is happening in each example. Be sure to indicate which examples you are describing. Be complete and use complete sentences.

- Experimental phase -

Using information given above and from your observations, your mission is to design, run, and save simulations of any three of the following:

1. Solar system with one sun and one orbiting planet (having one orbiting moon).

2. Solar system having one sun and three planets.

3. Solar system having two suns- each sun has one orbiting planet.

4. Solar system having one sun, one planet, and an approaching asteroid which gets captured into orbit by the planet

(the asteroid becomes a moon).

5. Solar system having one sun and five planets.

6. Two objects approach each other, capture each other, and orbit one another.

7. Solar system with one star, nine planets, and a total of thirteen moons. All planets and moons must eventually fall into the sun.

8. Solar system with one sun and two planets. One of the planets has an orbiting moon which must be "taken" by the second planet.

9. Your very own system - made to do what you want it to do.

- Evaluation phase -

1. Collect your written descriptions of the systems that you examined before creating your own systems.

2. If you selected Experimental Phase number 9 above, write a description of what your system illustrates. Attach this to your other descriptions.

3. Write out a description of what a simulation is and how it might be useful to scientists.

4. After completing this assignment, write out - in your own words - your definition of a system.

5. Hand in steps 1 - 4 of this Evaluation phase and demonstrate your saved simulations to your instructor.