let aVelocity = 0.03;

​

function setup() {

  createCanvas(560,390);

}

​

function draw() {

  background(220);

  let amplitude = 200;

  let x = amplitude * sin(angle);

  angle += aVelocity; //use the concept of angular velocity to increment an  angle variable

​

  translate(width/2, height/2);

  stroke(50);

  strokeWeight(2);

  fill(63,63,147);

  line(0, 0, x, 0);

  ellipse(x, 0, 48, 48);

}