Gravity help?

OreoEating · November 2015

Hey, so I have a question about the gravity of two objects acting on one object. I heard that you just need to find the net gravitational force, but it's not working for me, as the ball just goes in a different direction. Help, please?

PVector location1;
PVector velocity1;
PVector acceleration1;
PVector locationSun;
PVector locationSun2;
PVector distance;
float r;
float r1;
float vSun = 1;

void setup() {
  size(600, 600);

  location1 = new PVector(350, 30);
  velocity1 = new PVector(6, 0);
  acceleration1 = new PVector(0, 0);

  locationSun = new PVector(100, 300);
  locationSun2 = new PVector(500, 300);
}

void draw() {
  background(0);
  r = dist(location1.x, location1.y, locationSun.x+locationSun2.x+100, locationSun.y+locationSun2.y+100);

  if ( r < 50 ) {
    r = 50;
  }

 /* println(acceleration1.x);
  println(locationSun.x);
  println(acceleration1.x);
  println(acceleration1.x);*/

  acceleration1.x = ((locationSun.x - location1.x)*100000/pow(r, 3)) + (locationSun2.x - location1.x)*100000/pow(r, 3);
  acceleration1.y = ((locationSun.y - location1.y)*100000/pow(r, 3)) + (locationSun2.y - location1.y)*100000/pow(r, 3);

  velocity1.add(acceleration1);
  location1.add(velocity1);

  //locationSun.x += vSun;

  if ((locationSun.x >= width) || (locationSun.x <= 0)) {
    vSun *= -1;
  }

  ellipse(locationSun.x, locationSun.y, 50, 50);
  ellipse(locationSun2.x, locationSun2.y, 50, 50);
  ellipse(location1.x, location1.y, 20, 20);

}

rapatski · November 2015

Yes indeed, though an easier and slightly more intuitive way would simply be to add each force in turn to the acceleration of the particle. Do look up the reference for PVector; many of the operations you can do with vector math: you don't have to compute each component individually.