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;
}