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/************************************************************************************************
* Program name : Zero Gravity *
* Program ver. : 2.0 *
* Created by : SharpDevelop *
* Code author : Perić Željko *
* Code language : C# *
* Date created : 05.02.2012 *
* Time created : 20:44 *
* *
* *
* Program Description : *
* *
* Simple console application for calculating body altitude , *
* distance between planet and body , where the influence *
* of the gravitational field of planet is insignificant , *
* gravity force between planet and body is less or equal 0,001 N. *
* *
* Math formula : F = M * m * G / ( R + r + h )^2 *
* *
* F - gravity force N *
* M - mass of planet Kg *
* m - mas of body Kg *
* G - gravity constant N * m^2 / Kg^2 *
* R - planet radius m *
* r - body radius m *
* h - distance m *
* *
* Program accepts scientific format for large and small numbers. *
* *
* 4,3 e+5 = 4,3 * (10 ^ 5) = 4 300 000 e+5 stands for 10 raised to +5th power *
* *
* 587 e-5 = 587 * (10 ^-5) = 0,00587 e-5 stands for 10 raised to -5th power *
* *
* To enter such number , just type in 4,3e+5 or 587e-5 *
* *
* Number range that this program accept is from 1,7 e-308 up to 1,7 e+308 *
* *
* It is expected that entered values for calculation have adequate planet/body ratio , *
* other wise program looses logical sense , but still it shall give correct result. *
* *
* Example : Make calculation for planet Earth and simple ball *
* *
* *
* planet Earth : M = 5,98 e+024 Kg *
* R = 6378 e+003 m *
* *
* simple ball : m = 2,50 e-001 Kg *
* r = 3,00 e-001 m *
* *
* Result should be : h = 3,09401194708158 e+005 Km or 309 401,194708158 Km *
* *
* This result presumes ideal condition , that there are only these two bodies *
* in universe with no other forces of any kind that can influence them. *
* *
* Program Accuracy Notice : *
* *
* All calculations in program are executed using double type of variable. *
* By default , a double value contains 15 decimal digits of precision , *
* although a maximum of 17 digits is maintained internally. *
* Result is shown in scientific format , rounded at fourteen decimals. *
* This could cause fatal error because , in some cases for accurate result , *
* many more digits are significant , especially when very large or very small *
* numbers are involved. *
* *
* Gravity constant value is rounded at two decimal places , *
* and usually input values that user type in , have it's own precision error... *
* *
* So the result that this program gives is always approximate and never 100 % accurate ! *
* *
* *
* All the best, *
* Author. *
************************************************************************************************/
using System;
namespace Zero_gravity
{
class Program
{
public static void Main(string[] args)
{
//
// Description of Main().
//
// Set values to necessary variables for calculation.
//
// Calculate gravity force at zero altitude
// and show result on console screen
// as formatted string representation of number.
//
// Simulation of body flying away from planet :
//
// Calculate strength of gravity force for every body altitude
// incremented by altitude increment value and show result on
// console screen as formatted string representation of number.
//
// Simulation end's when strength of gravity force becomes
// equal or less than 0,001 N.
//
// Calculate distance between body and planet where gravity force is equal 0,001 N
// and show result on console screen as formatted string representation of number.
//
// Calculated altitude result is divided by 1000 m and represents distance in Km.
//
//
// variable declaration
//
// gravity constant , just two decimal places !!!
const double GravityConstant = 6.67e-11;
double PlanetRadius = 0;
double BodyRadius = 0;
double PlanetMass = 0;
double BodyMass = 0;
double BodyAltitude = 0;
double GravityForce = 0;
double AltitudeIncrement = 0;
double helper = 0;
double helper1 = 0;
// scientific (exponential) number format with 14 decimals
// first three decimals shall always be shown on console
// next eleven are optional , if not equal zero
string format1 = "0.000############ e+000";
// scientific (exponential) number format rounded at 6 decimals
string format2 = "0.000000 e+000";
// cursor column position
int Column = 0;
// cursor row position
int Row = 0;
// counter
double i = 0;
//
// set console : title , window & buffer size , fore & back color and clear console
//
Console.Title = " Zero Gravity - by Perić Željko (periczeljkosmederevo@yahoo.com)";
Console.SetWindowSize(80,42);
Console.SetBufferSize(80,42);
Console.ForegroundColor = ConsoleColor.Green;
Console.BackgroundColor = ConsoleColor.Black;
Console.Clear();
//
// declare new variable 'key' and set it's initial value to 'Y' - 'Yes' ,
// used for getting user's answer from keyboard at the end of program
//
ConsoleKeyInfo key = new ConsoleKeyInfo('Y',ConsoleKey.Y,true,true,true);
//
// restart calculation if answer is 'Y' - 'Yes'
//
while(key.Key == ConsoleKey.Y)
{
//
// set variables to initial values
//
PlanetRadius = 0;
BodyRadius = 0;
PlanetMass = 0;
BodyMass = 0;
BodyAltitude = 0;
GravityForce = 0;
AltitudeIncrement = 0;
helper = 0;
helper1 = 0;
Column = 0;
Row = 0;
i = 0;
//
// write program description to user
//
Console.Clear();
Console.Write("********************************************************************************");
Console.Write(" ");
Console.Write(" Program for calculating body altitude ");
Console.Write(" ");
Console.Write(" ( distance between planet and body ) ");
Console.Write(" ");
Console.Write(" where the influence of the gravitational field ");
Console.Write(" ");
Console.Write(" of planet is insignificant, F is less or equal 0,001 N ");
Console.Write(" ");
Console.Write("********************************************************************************");
Console.Write("\n");
//
// get inital values
//
// warning ,
// there is no part for validation
// of relevance of entered number
// that part try to write yourself
//
// To enter very large or very small number
// use scientific format that program recognize.
//
// Mass of Sun M = 1,99 e+30 Kg
//
// type in 1,99e+30 or 1,99e30 or 1,99E+30 or 1,99E30
//
// Gravity constant G = 6,67 e-11 N * m^2 / Kg^2
//
// type in 6,67e-11 or 6,67E-11
//
//
Console.Write(" Enter mass of planet in kilograms M = ");
PlanetMass = double.Parse(Console.ReadLine().ToString());
Console.Write("\n");
Console.Write(" Enter radius of planet in meters R = ");
PlanetRadius= double.Parse(Console.ReadLine().ToString());
Console.Write("\n");
Console.Write(" Enter mass of body in kilograms m = ");
BodyMass = double.Parse(Console.ReadLine().ToString());
Console.Write("\n");
Console.Write(" Enter radius of body in meters r = ");
BodyRadius= double.Parse(Console.ReadLine().ToString());
Console.Write("\n");
Console.Write(" Enter altitude increment in meters h = ");
AltitudeIncrement = double.Parse(Console.ReadLine().ToString());
Console.Write("\n");
//
// calculate gravity force at zero altitude , and write result
//
GravityForce = BodyMass*PlanetMass*GravityConstant;
helper = PlanetRadius + BodyRadius + BodyAltitude;
helper = helper * helper;
GravityForce = GravityForce / helper;
//
// show result as string using format1
//
Console.Write("********************************************************************************");
Console.Write(" ");
Console.Write(" Garvity force at zero altitude F = ");
Console.Write(GravityForce.ToString(format1) + " N ");
Console.Write("\n");
Console.Write(" ");
Console.Write("********************************************************************************");
Console.Write("\n");
//
// get current cursor column and row position
//
Column = Console.CursorLeft;
Row = Console.CursorTop;
Console.Write(" Press any key to continue . . .");
Console.ReadKey(true);
//
// set cursor position
//
Console.SetCursorPosition(Column,Row);
Console.Write(" ");
Console.Write(" ");
Console.Write(" ");
Console.Write(" ");
Console.Write("********************************************************************************");
//
// increase altidude until gravity force becomes less or equal 0,001
//
while (GravityForce > 0.001) // here you can change condition for gravity strength
{
BodyAltitude = BodyAltitude + AltitudeIncrement;
GravityForce = BodyMass*PlanetMass*GravityConstant;
helper = PlanetRadius + BodyRadius + BodyAltitude;
helper = helper * helper;
GravityForce = GravityForce / helper;
i++;
//
// this question increases speed of calculation by
// writing on console every 1 000 000-th result
//
if(i%1000000 == 0)
{
//
// write results without changing position of text
//
Console.SetCursorPosition(Column,Row);
//
// show result as string using format2
//
Console.Write(" Gravity force F = ");
Console.Write(GravityForce.ToString(format2) + " N ");
Console.Write("\n\n");
Console.Write(" At achieved altitude h = ");
Console.Write((BodyAltitude/1000).ToString(format2) + " Km ");
}
}
//
// write final results without changing position of text
//
Console.SetCursorPosition(Column,Row);
//
// show result as string using format1
//
Console.Write(" Gravity force F = ");
Console.Write(GravityForce.ToString(format1) + " N ");
Console.Write("\n\n");
Console.Write(" At achieved altitude h = ");
Console.Write((BodyAltitude/1000).ToString(format1) + " Km ");
Console.Write("\n\n");
//
// calculate zero gravity altitude directly trough math calculation
// for F = 0,001 N altitude h = ?
//
GravityForce = BodyMass*PlanetMass*GravityConstant;
helper1 = GravityForce / 0.001;
helper1 = Math.Sqrt(helper1);
if (helper1.ToString() == (PlanetRadius + BodyRadius).ToString())
{
helper1 = 0;
}
else
{
helper1 = (helper1 - PlanetRadius - BodyRadius) / 1000;
}
//
// show result as string using format1
//
Console.Write("********************************************************************************");
Console.Write(" ");
Console.Write(" Gravity force F = 0,001 N ");
Console.Write(" ");
Console.Write(" At calculated altitude h = " + helper1.ToString(format1) + " Km \n");
Console.Write(" ");
Console.Write("********************************************************************************");
Console.Write("\n");
//
// end of program
//
Console.Write(" Another calculation (y/n) ? ");
key = Console.ReadKey(true);
}
}
}
}
/************************************************************************
* Program Licence : *
* *
* Copyright 2012 , Perić Željko *
* (periczeljkosmederevo@yahoo.com) *
* *
* According to it's main purpose , this program is licenced *
* under the therms of 'Free Software' licence agreement. *
* *
* If You do not know what those therms applies to *
* please read explanation at the following link : *
* (http://www.gnu.org/philosophy/free-sw.html.en) *
* *
* Since it is Free Software this program has no warranty of any kind. *
************************************************************************
* Ethical Notice : *
* *
* It is not ethical to change program code signed by it's author *
* and then to redistribute it under the same name , especially *
* if it is incorrect. *
* *
* It is recommended that if you make improvement in program code , *
* to make remarks of it and then to sign it by Your's name , *
* for further redistribution as new major version of program. *
* *
* Author name and references of old program code version should be *
* kept , for tracking history of program development. *
* *
* For any further information please contact code author at his email. *
************************************************************************/
/************************************
* List Of Revisions *
************************************
* Minor revision of version 1.0 *
* Author 21.02.2013 *
* new comments added *
* New version number 1.1 *
************************************
* Major revision of version 1.1 *
* Author 22.02.2013 *
* new comments added *
* console user interface changed *
* number format changed *
* spelling checked *
* program licence added *
* New version number 2.0 *
************************************/
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