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-
- Gravity Well
-
- Celestial Motion Simulator
-
- by Gary Teachout
-
- Freeware Copyright 1989
-
- Gravity Well simulates the motion of up to twenty bodies in Newtons
- universe. Distance, time and mass are in canonical units (UGC=1). The
- position, velocity and mass of each body may be entered with the mouse or
- by typing the numbers into the boxes in the data window and clicking the
- enter button. The view of the simulation may be scaled, rotated in three
- dimensions or repositioned using the buttons in the view control window.
- When two bodies collide one absorbs the other in a way that mass and
- momentum are conserved.
-
- Continuous motion is aproximated by a sequence of discrete steps. At
- each step the acceleration of each body is added to its velocity then the
- velocity of each body is added to its position and the new position is
- displayed. The variable Time Step controls the maximum amount of time
- covered by each step. During close encounters the actual step size is
- reduced to minimize errors.
-
- Menus:
- QUIT Exits the program.
- Open Window Opens the window or moves it to the front.
- Control
- Start Starts or continues the simulation.
- Stop Halts the simulation.
- Set Makes start settings equal current settings.
- Reset Makes current settings equal start settings.
-
- View Control buttons:
- Follow Causes the display to be centered on the selected body.
- Center Allows you to use the mouse to reposition the display.
- Trails Starts or stops the red trails.
- -Rotate- These buttons change the orientation of the view.
- -Zoom- These buttons change the scale of the view.
-
- Data window buttons:
- Load Loads a simulation from a file.
- Save Saves a simulation to a file.
- New Clears all data.
- 1,2...20 Buttons numbered 1 - 20 select the current body. All
- input goes to the selected body.
- Position After clicking this button you may use the mouse to
- reposition the selected body in the view windows.
- Velocity After clicking this button you may use the mouse to
- change the velocity of the selected body in the view
- windows.
- Mass After clicking this button you may use the mouse to
- change the mass of the selected body in the view windows.
- Delete Removes the selected body from the simulation.
- Zero M Zero Momentum. Adjusts the velocity of all bodies in the
- simulation so that the totel momentum is zero. This
- prevents the system from drifting out of the display.
- Start Starts or continues the simulation (Same as Start menu
- item).
- Create Input mode. This allows bodies not yet part of the
- simulation to be selected.
- Enter Records data in from the input boxes.
-
- Data window input boxes:
- File Name AmigaDOS file name for loads and saves.
- Comment Space for anything you want to say about this simuation.
- Time Step Maximum step size in canonical units (press RETURN to
- enter).
- Magic Magic controls how the program handels close encounters.
- The program is more acurate with large numbers but will
- run more slowly. Numbers from 50 to 200 are typical.
- Name The name or a comment for the selected body.
- Mass Mass of selected body. Each body may have zero or more
- mass.
- Radius Size of selected body. This is used only to test for
- collisions.
- Start Position Inital position vector components of selected body.
- Start Velocity Inital velocity vector components of selected body.
-
- The Gravity-Well directory contains the following example simulation files.
-
- System Sol and the planets. To view just the outer planets
- use a larger Time Step and small Magic. To view just the
- inner planets use a smaller Time Step.
- Lagrange The Earth the Moon and their stable Lagrange points
- (trojan points).
- Neighborhood Sol and some stars from the local neighborhood.
-
-
- Gravity Well may be copied and distributed on a not for profit basis.
-
- Please send any coments, suggestions, bug reports, donations (accepted
- but not required) or outstanding simulations to:
-
- Gary Teachout
- 10532 66 place, W
- Everett, Wa, 98204
-
- USA
- North America
- Earth
- Sol
- Carina Cygnus
- Milky Way
-
- Support The National Space Society
-
-