var velocity = 0;

var acceleration = 1.63;

​

function setup() {

  createCanvas(400, 400);

}

​

function draw() {

  //update

  if (ballY > height){

    velocity = -velocity * 0.9;

    ballY = height;

  }

  velocity += acceleration;

  ballY += velocity;

  //draw

  background(220);

  noStroke();

  fill(0);

  ellipse(width/2, ballY, 10, 10);

}