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simple ball physics not working properly

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Hi can you please help me, my balls get pushed away abrubtly when colliding sometimes,im keeping my velocities less than my ball radiuses so it can not be that, i have done loads of experimentation but with no joy. (cr=0.4; mass=1;) please av a gander at my following code written in flash cs3 thankyou in advance. for (var i1:uint=0;i1<CARTOTAL-1;i1++) { for (var i2:uint=i1+1;i2<CARTOTAL;i2++) { var dx:Number=cararray[i1].x-cararray[i2].x, dy:Number=cararray[i1].y-cararray[i2].y, d:Number=Math.sqrt(dx*dx+dy*dy), r1:Number=19, r2:Number=r1; if (d<=(r1+r2)) { // component of velocity in the direction (dx,dy) var vp1:Number=cararray[i1].velx*dx/d+cararray[i1].vely*dy/d, vp2:Number=cararray[i2].velx*dx/d+cararray[i2].vely*dy/d, dt:Number=(r1+r2-d)/(vp1+vp2); // move back cararray[i1].x-=cararray[i1].velx*dt; cararray[i1].y-=cararray[i1].vely*dt; cararray[i2].x-=cararray[i2].velx*dt; cararray[i2].y-=cararray[i2].vely*dt; dx=cararray[i1].x-cararray[i2].x; dy=cararray[i1].y-cararray[i2].y; d=Math.sqrt(dx*dx+dy*dy); // unit vector in the direction of the collision var ax:Number=dx/d , ay:Number=dy/d; // projection of the velocities var va1:Number=( cararray[i1].velx*ax+cararray[i1].vely*ay), vb1:Number=(-cararray[i1].velx*ay+cararray[i1].vely*ax), va2:Number=( cararray[i2].velx*ax+cararray[i2].vely*ay), vb2:Number=(-cararray[i2].velx*ay+cararray[i2].vely*ax); // new velocities after collisions var vap1:Number=va1+(1+cr)*(va2-va1)/(1+cararray[i1].mass/cararray[i2].mass), vap2:Number=va2+(1+cr)*(va1-va2)/(1+cararray[i2].mass/cararray[i1].mass); // undo the projections (new velocities after collision) cararray[i1].velx=vap1*ax-vb1*ay; cararray[i1].vely=vap1*ay+vb1*ax; cararray[i2].velx=vap2*ax-vb2*ay; cararray[i2].vely=vap2*ay+vb2*ax; // move forward cararray[i1].x+=cararray[i1].velx*dt; cararray[i1].y+=cararray[i1].vely*dt; cararray[i2].x+=cararray[i2].velx*dt; cararray[i2].y+=cararray[i2].vely*dt; } } }

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