Gravitacija - Gravity Force
Program "Gravity Force" je namenjen za izračunavanje vrednosti jačine sile privlačenja dva tela, odnosno Gravitacione sile.
Sve što se tiče Gravitacije možete pronaći na dole navedenim adresama :
Pored ovih adresa ima još mnogo mesta na internetu posvećenih ovoj temi. Ono što je bitno za programera koji rešava ovakav tip problem jeste kako se izračunava jačina gravitacione sile. Na osnovu gore navedene literature :
Postupak za izračunavanje gravitacione sile je sada jasan. Neophodno je da korisnik programa unese vrednosti promenljivih M, m i r . Gravitaciona konstanta , samo ime joj kaže je konstanta s vrednošću, koja iznosi približno 6.67E-11 Nm^2/Kg^2. Po unosu, vrednosti se jednostavno ubace u gore navedenu formulu i dobijamo vrednost jačine sile privlačenja između dva tela odnosno jačinu gravitacione sile. Algoritam pokušajte da napravite sami, u međuvremenu pogledajte i proučite programski kod :
/************************************************************************************************
* Program name : Gravity force *
* Program ver. : 2.0 *
* Created by : SharpDevelop *
* Code author : Perić Željko *
* Code language : C# *
* Date created : 03.02.2012 *
* Time created : 15:22 *
* *
* *
* Program Description : *
* *
* Simple console application for calculating strength of gravity force ( F ) , *
* between two celestial bodies with known masses ( M and m ) , *
* and known distance between centers of body masses ( r ). *
* *
* Math formula : F = M * m * G / r ^ 2 *
* *
* Try to calculate gravity force between Sun and Earth. *
* *
* Mass of Sun M = 1,99 e+30 Kg *
* Mass of Earth m = 5,98 e+24 Kg *
* Distance r = 1,5 e+11 m *
* Gravity constant G = 6,67 e-11 N * m^2 / Kg^2 *
* *
* Result should be F = 3,527748177777778 e+22 N (newton) N = Kg * m / s^2 *
* *
* 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 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 *
* *
* 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 Gravity
{
class Program
{
public static void Main(string[] args)
{
//
// Description of Main.
//
// Declare new object named Start ,
// as an instance of GravityForce class ,
// and call it's method Calculate().
//
GravityForce Start = new GravityForce();
Start.Calculate();
}
}
class GravityForce
{
public void Calculate()
{
//
// Description of Calculate().
//
// Set values to necessary variables for calculation ,
// by calling GetValue(int cursor_x , int cursor_y) method.
// Calculate strength of gravity force and show result on
// console screen as formatted string representation of number.
//
//
// declaration of variables
//
const double G = 6.67e-11; // gravity constant , just two decimal places !!!
double M = 0; // mass of first body
double m = 0; // mass of second body
double r = 0; // distance between centers of body masses
double F = 0; // gravity force
string Result = ""; // result of calculation represented as string
//
// set console : title , window & buffer size , fore & back color and clear console
//
Console.Title = " Gravity - by Perić Željko (periczeljkosmederevo@yahoo.com)";
Console.SetWindowSize(70,40);
Console.SetBufferSize(70,40);
Console.ForegroundColor = ConsoleColor.Green; // text color
Console.BackgroundColor = ConsoleColor.Black; // back color
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
//
M = 0;
m = 0;
r = 0;
F = 0;
//
// write program description to user
//
Console.Clear();
Console.Write("**********************************************************************");
Console.Write(" ");
Console.Write(" Program for calculating strength of gravity force between two bodies ");
Console.Write(" ");
Console.Write("**********************************************************************");
//
// get value for M
//
Console.SetCursorPosition(0,5);
Console.Write(" ");
Console.Write(" Enter value for mass of first body in kilograms : ");
Console.Write(" ");
Console.Write(" M = ");
Console.Write(" ");
Console.Write("**********************************************************************");
M = GetValue(5,8); // Call GetValue(int cursor_x , int cursor_y) method
//
// get value for m
//
Console.SetCursorPosition(0,11);
Console.Write(" ");
Console.Write(" Enter value for mass of second body in kilograms : ");
Console.Write(" ");
Console.Write(" m = ");
Console.Write(" ");
Console.Write("**********************************************************************");
m = GetValue(5,14); // Call GetValue(int cursor_x , int cursor_y) method
//
// get value for r
//
Console.SetCursorPosition(0,17);
Console.Write(" ");
Console.Write(" Enter value for distance between centers of body masses in meters : ");
Console.Write(" ");
Console.Write(" r = ");
Console.Write(" ");
Console.Write("**********************************************************************");
r = GetValue(5,20); // Call GetValue(int cursor_x , int cursor_y) method
//
// write values of parameters on console with it's basic units of measurement ,
// number format is scientific , rounded at four decimals that must be shown
//
Console.SetCursorPosition(0,23);
Console.Write(" ");
Console.Write(" M = " + M.ToString("0.0000 e+000") + " Kg" + "\n");
Console.Write(" m = " + m.ToString("0.0000 e+000") + " Kg" + "\n");
Console.Write(" r = " + r.ToString("0.0000 e+000") + " m" + "\n");
Console.Write(" G = " + G.ToString("0.0000 e+000") + " N * m^2 / Kg^2" + "\n");
Console.Write(" ");
Console.Write("**********************************************************************");
//
// calculate gravity force
//
r = r*r;
F = (M*m*G)/r;
//
// set value to Result ,
// number format is scientific rounded at fourteen decimals ,
// first four decimals must be shown even if equal zero ,
// next ten decimals are shown optionally , if not zero
//
Result = F.ToString("0.0000########### e+000");
//
// show result on console
//
Console.Write(" ");
Console.Write(" Strength of gravity force between two bodies is : ");
Console.Write(" ");
Console.Write(" F = " + Result + " N (newton) N = Kg * m / s^2 " + "\n");
Console.Write(" ");
Console.Write("**********************************************************************");
//
// end of program
//
Console.Write(" ");
Console.Write(" Another calculation (y/n) ? ");
key = Console.ReadKey(true);
}
}
private double GetValue(int cursor_x , int cursor_y)
{
//
// Description of GetValue(int cursor_x , int cursor_y).
//
// Controls input from keyboard on specified console position.
// Gets word from keyboard , preventing that entered word length
// is greater then 60 letters , and securing that letters entered
// are only from the list of possible letters.
//
// 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
//
// Instead of ',' use '.' if local regional settings
// declare point instead comma for decimal separator.
//
//
// declaration of variables
//
const string possible_letters = "1234567890eE+-,."; // list of possible letters
string word = ""; // entered word from keyboard
string letter = ""; // last typed letter on keyboard
int length = 0; // length of word
double number = 0; // converted word to double value
bool IsNumber = false; // number relevance switch
//
// get new word from keyboard ,
// repeat until user has entered correct double value
//
while(IsNumber == false)
{
word = "";
letter = "";
length = 0;
number = 0;
Console.SetCursorPosition(cursor_x, cursor_y);
Console.Write(" ");
Console.SetCursorPosition(cursor_x, cursor_y);
//
// get new letter from keyboard until pressed key is 'Enter'
// if typed key is 'Delete' or 'Backspace' delete last letter from word
//
ConsoleKeyInfo key = new ConsoleKeyInfo();
while(key.Key != ConsoleKey.Enter)
{
key = Console.ReadKey();
if(key.Key == ConsoleKey.Backspace || key.Key == ConsoleKey.Delete)
{
length--;
if(length < 0)
{
length = 0;
}
word = word.Substring(0, length);
Console.SetCursorPosition(cursor_x, cursor_y);
Console.Write(" ");
Console.SetCursorPosition(cursor_x, cursor_y);
Console.Write(word);
}
else
{
letter = key.KeyChar.ToString();
if(possible_letters.Contains(letter ))
{
length++;
if(length < 61)
{
word = word + letter;
}
else
{
length = 60;
Console.SetCursorPosition(cursor_x, cursor_y);
Console.Write(" ");
Console.SetCursorPosition(cursor_x, cursor_y);
Console.Write(word);
}
}
else if(!possible_letters.Contains( letter ))
{
Console.SetCursorPosition( cursor_x, cursor_y );
Console.Write(" ");
Console.SetCursorPosition( cursor_x, cursor_y );
Console.Write(word);
}
}
}
//
// check does entered word represents positive real number greater then zero
// if not , write error message and ask for new entry
//
IsNumber = double.TryParse(word.ToString(), out number);
if(IsNumber)
{
if(number <= 0)
{
Console.Beep();
Console.SetCursorPosition(0, cursor_y + 4);
Console.Write(" Entry error ! Entered value must be greater then zero ! ");
Console.Write(" ");
Console.Write(" Press any key to continue ...");
Console.ReadKey(true);
Console.SetCursorPosition(0, cursor_y + 4);
Console.Write(" ");
Console.Write(" ");
Console.Write(" ");
IsNumber = false;
}
}
else
{
Console.Beep();
Console.SetCursorPosition(0, cursor_y + 4);
Console.Write(" Entry error ! You have entered incorrect value ! ");
Console.Write(" ");
Console.Write(" Press any key to continue ...");
Console.ReadKey(true);
Console.SetCursorPosition(0, cursor_y + 4);
Console.Write(" ");
Console.Write(" ");
Console.Write(" ");
}
}
//
// return entered number
//
return number;
}
}
}
/************************************************************************
* 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 author 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 15.02.2013 *
* new comments added *
* console user interface changed *
* number format changed *
* spelling checked *
* program licence added *
* New version number 1.1 *
************************************
* Major revision of version 1.1 *
* Author 20.02.2013 *
* class GravityForce created *
* New version number 2.0 *
************************************/
Prilikom unosa vrednosti možete koristiti takozvani naučni format brojeva primer: 230 000 000 000 = 2,3e+11.
Vodite računa da li je kod vas definisan zarez za razdvajanje decimala od celih brojeva ili tačka.
Pokušajte da izračunate gravitacionu silu između Sunca i Zemlje :
* Masa Sunca M = 1,99 e+30 Kg
* Masa Zemlje m = 5,98 e+24 Kg
* Rastojanje r = 1,5 e+11 m
* Rezultat F = 3,527748 e+22 N
Sada uz pomoć ovog programa možete izračunati kojom silom Zemlja privlači Mesec , ili uz manje modifikacije možete pronaći željenu masu tela kako bi sila privlačenja bila određene jačine, ili na kom odstojanju tela moraju da budu da bi sila bila određene jačine. Još puno raznih proračuna se može napraviti uz pomoć ovakvog programa. Recimo praćenje opadanja ili porasta jačine gravitacione sile između dva tela kada se rastojanje smanjuje ili povećava za određeni korak (distancu u metrima). Ili grafički prikazati srazmerno opadanje mase jednog od tela kako se smanjuje gravitaciona sila kako bi rastojanje ostalo isto.U prilogu se nalazi "Gravity force open source.zip" arhiva s kompletnim rešenjem pisanim za IDE SharpDevelop C#, koje možete preuzeti i menjati po želji. Neophodan .Net framework 4.0 ili noviji.