Thread: Physics between two balls, incorrect calculated angle. Help!

I've been stuck on this one for a while. If you scroll down to the while loop there is some code that calculates the angle of a triangle created by two circles colliding. The problem is, The angle between the hypotenuse / x axis, and the angel between the hypotenuse / y axis never go above 65 degrees and i have no clue why, please help!

import java.awt.Color;
import java.awt.Graphics;
import java.util.Random;
 
import javax.swing.JComponent;
import javax.swing.JFrame;
 
public class MainTest extends JFrame {
    public rectt g = new rectt();
 
    public static void main( String[] args ) throws InterruptedException {
        MainTest t = new MainTest();
 
        int particles = 2;
        int radius =100;
        Random number = new Random();
        t.setSize( 1800, 1000 );
        t.setVisible( true );
        t.getContentPane().add( t.g );
        t.setDefaultCloseOperation(EXIT_ON_CLOSE);
 
        int xVelocity[] = new int[particles+1];
        int yVelocity[] = new int[particles+1];
        int mass[] = new int[particles+1];
        for(int z=1;z<particles+1;z++){
        	xVelocity[z]= (20-number.nextInt(40));
        	yVelocity[z]= (20-number.nextInt(40));
            mass[z]=5;
        }
 
 
        while ( true ) {
        	for(int z=1;z<particles+1;z++){
        		if (t.g.x[z] <=0 + radius/2|| t.g.x[z]>=1600-radius/2){
        			xVelocity[z] = xVelocity[z]*-1;
        		}
        		if (t.g.y[z] <=0 || t.g.y[z]>=900){
        			yVelocity[z] = yVelocity[z]*-1;
        		}
        		if (t.g.y[z]>=900){
        			yVelocity[z]= yVelocity[z]-1;
        		}
        		for (int c=1;c<particles+1;c++){
        			String temp1 = Integer.toString(t.g.x[c]);
        			String temp2 = Integer.toString(t.g.x[z]);
        			String temp3 = Integer.toString(t.g.y[c]);
        			String temp4 = Integer.toString(t.g.y[z]);
        			Double temp11 = Double.parseDouble(temp1);
        			Double temp22 = Double.parseDouble(temp2);
        			Double temp33 = Double.parseDouble(temp3);
        			Double temp44 = Double.parseDouble(temp4);
 
        			if (Math.sqrt(Math.pow(temp11-temp22,2)+Math.pow(temp33-temp44,2))<radius && Math.sqrt(Math.pow(temp11-temp22,2)+Math.pow(temp33-temp44,2)) !=0 && (temp11-temp22) !=0 && (temp33-temp44) !=0){
        				double hypotenuse = Math.sqrt(Math.pow(temp11-temp22,2)+Math.pow(temp33-temp44,2));
        				double x = (temp11-temp22);
        				double y = (temp33-temp44);
        				double hypx = Math.asin(((Math.sin(90)/hypotenuse)*y));
        				//double hypx = Math.acos((Math.pow(hypotenuse,2)-Math.pow(x,2)-Math.pow(y,2))/-2*x*y);
        				double hypy = Math.asin(((Math.sin(90))/hypotenuse)*x);
        				//System.out.println(Math.abs(Math.toDegrees(hypx))+90+Math.abs(Math.toDegrees(hypy)));
        				System.out.println(Math.toDegrees(hypx));
        				try {
        		                Thread.sleep(100);
        		            } catch ( InterruptedException e ) {
        		            }
            		}
        		}
 
        		yVelocity[z]= yVelocity[z]+1;
 
        		t.g.x[z] = t.g.x[z] + xVelocity[z];
                t.g.y[z] = t.g.y[z] + yVelocity[z];
                t.repaint();
        	}
            try {
                Thread.sleep( 10);
            } catch ( InterruptedException e ) {
            }
        }
}
 
    public void paintComponent( Graphics g ) {
        //g.clearRect( 0, 0, 0, 0 );
    }
}
 
 
class rectt extends JComponent {
 
    public static final long serialVersionUID = 1L;
 
    public int particles =2;
    public int radius =100;
 
    public int x[] = new int[particles+1];
    public int y[] = new int[particles+1];
    public int width[] = new int[particles+1];
    public int height[] = new int[particles+1];
    int done=0;
 
    public void paintComponent( Graphics g ) {
        g.setColor( Color.black );
        if (done==0){
        for(int z=1;z<particles+1;z++){
        	x[z]=800;
        	y[z]=500;
        	width[z]=radius;
        	height[z]=radius;
        	done=1;
        }
        }
        for(int z=1;z<particles+1;z++){
        	g.fillOval(x[z]-radius/2, y[z]-radius/2, width[z], height[z]);;
        	g.drawLine(1600, 0, 1600, 1000);
        	g.drawLine(x[z], y[z], x[z-1], y[z-1]);
        }
 
    }
}

Originally Posted by Norm

What variable is not getting the expected value? What values does it get?
Can you post a table of rows with two columns, one column showing the expected value the other showing the value that is incorrectly computed?

Ok so the two angles that i am calculating are hypx(the angle between the hypotenuse and the x axis), and hypy(the angle between the hypotenuse and the y axis). If you run the code you can see that when the two balls are almost vertical the hypx should be outputting a near 90 degree angle, but instead it outputs a near 65 degree angle. Likewise, when the balls are near horizontal to each other the hypy should be outputting a near 90 degree, but instead a near 65 degree angle is being outputted.

hopefully that should provide some insight.