float M = 0.8; // Mass
  float K = 0.2; // Spring constant
  float D = 0.92; // Damping
  float R = 100; // Rest position
  float ypos; // Position
  float v = 0.0; // Velocity
  float a = 0; // Acceleration
  float f = 0; // Force
  boolean released = false;
  void setup() {
    size(200, 200);
    ypos = height/2;
  }
  void draw() {
    background(200);
    if(released)move();
    ellipse(width/2, ypos , 50,50);
  }
  void move(){
    f = -K * (ypos - R); // f=-ky
    a = f / M; // Set the acceleration, f=ma == a=f/m
    v = D * (v + a); // Set the velocity
    ypos += v; // Updated position
    if(abs(v) < 0.01) {
      v = 0.0;
      released = false;
    }
  }
  void mouseMoved() {
    if(dist(mouseX,mouseY,width/2,ypos)<50)
      stroke(255,0,0);
    else
      stroke(0);
  }
  void mouseDragged() {
    released = false;
    ypos = mouseY;
  }
  void mouseReleased(){
    released = true;
  }