% Simulation
% By:  Jay Borthen
% A two point-mass gravitational system

clear all
close all

% Fun Fact - The Earth supposedly has a mass of 5.9736x10^24 kg
M1=550000000;  % kg
M2=125000000;  % kg
G=6.67384*10^(-11);  %N*(m/kg)^2

P_M1=[23 20];  % Initial point in space of mass 1
V_M1=[0.05 0.03];  % Initial velocity vector of mass 1

P_M2=[10 15];  % Initial point in space of mass 2
V_M2=[-0.02 0.1];  % Initial velocity vector of mass 2



for t=1:1000  % seconds

rVec=P_M2-P_M1;

plot(P_M1(1),P_M1(2),'b.')
hold on
plot(P_M2(1),P_M2(2),'r.')
axis([-5 50 -5 50])
hold on

r=sqrt((rVec(1)^2)+(rVec(2)^2));
F=G.*(M1.*M2)/(r.^2);

F1=F.*rVec;
F2=-F.*rVec;

V_M1=V_M1+(F1/M1);
P_M1=P_M1+(V_M1)/2;

V_M2=V_M2+(F2/M2);
P_M2=P_M2+(V_M2)/2;

grid on
pause(0.05)
end