| < User Manual Home | 2 User manual > |
This User Manual describes the application by chapters. The first chapter describes what this application is, what it is used for, whom it is proposed to.
The second section begins with describing the program environment, installing the program and introducing you to the program model, than describes the program operation in detail.
Subsections are built to each other. Firstly, the objects (bodies, groups, system) used in the program are described. The section Compute position describes the mathematical and physical background to the program, while Display defines priorities of graphical objects. The section Mouse pointer outlines any shape the mouse pointer may have, while StatusBar does the status bar information fields. The section Bookmark outlines recording the simulation moments, while Control Panel does controlling the simulation. The section Program states deals with options for editing an object, simulation control and various program states in detail.
In the Supplement, dialog windows and menus for the program are comprised.
Throughout the manual, the Left mouse button refers to the primary mouse button, and the Right mouse button to the secondary one.
Gravity is a program to simulate the path of move for bodies (i.e. objects with mass) altered by the gravity drive between each other, i.e. a gravity simulator.
By using this program, gravitational attraction may be better learned. From the simplest orbit to complicated galaxy crashes, there is a wide variety of motions by gravity. On simulating the motion of two bodies, it is conspicuous to model the elliptic orbit around each other’s mass center of the Sun and the Earth or the path of a rocket as leaving the Earth with the speed of escape or the see-saw maneuver of a space probe, when gaining speed (kinetic energy) from a planet. By modeling multiple bodies, you may observe the perturbance of planets interfering with each other, ejecting a body from the system or when a planet capturing a body that arrives from the outside and making it a satellite of its own.
This program is used to simulate planetary systems either stable (stationary for a long time) or unstable (changing in a relatively short time). There are stable systems e.g. the Solar System featured by their orbits of almost circular and coplanar (except Pluto but it has a minor mass and is too far from small planets of earth type). It may be an example of unstable systems, where planets move along a prolate path and a high-mass body may get too near to a low-mass one causing to the smaller one to gain overspeed and to leave the system or to take the bearing on the central star and smash into it.
The “life” of such planetary systems is modeled by computer simulation alone. On modeling, you shall choose between accuracy and velocity, as computer resources are limited. Gravity uses double precision floating-point number representation to count orbital elements, made in C language at low level (MS Visual C, Win32 SDK) to ensure high processing rate. Just the computer memory and graphical objects of the operating system that can be displayed simultaneously limits the number of bodies.
Gravity is not a closed system to the effect that data created or processed in it can also be used by other programs. Data is exported into text files or imported back from them for external programs to use or change them (see Description of the export/import file). For example, you may create bodies for the program using a word processor. During simulation, computing results may even saved in a log file to serve as input data for other programs (see Log).
As a fundamental physical phenomenon, gravity is on curriculum at elementary and secondary schools and at vocational higher schools, thus it is an aid for both pupils and teachers, when they can see orbital paths in addition to imaging them. Sitting before the computer, a process that lasts effectively for years may take place in a few seconds, the Kepler's and Newton's law are understood in a shorter time.
Gravity is proposed to schools, teachers, students, undergraduates in physics and anyone interested in natural sciences, physics or to those just like spectacular programs.
| < User Manual Home | 2 User manual > |