let angleV = 0;

let angleA = 1;

let bob;

let origin;

let gravity = 3;

function setup() {

  createCanvas(600, 600);

  angle = PI / 2;

  bob = createVector();

  len = 200;

  origin = createVector(300, 0);

}

​

function draw() {

  background(80, 50);

  let force = gravity * sin(angle);

  angleA = (200 * force) / len;

​

  angleV += angleA;

  angle += angleV;

  bob.x = len * sin(angle) + origin.x;

  bob.y = len * cos(angle) + origin.y;

  stroke(0);

  strokeWeight(8);

  line(origin.x, origin.y, bob.x, bob.y);

  fill(100);

  stroke(0);

  circle(bob.x, bob.y, 54);

}

​