bob,

    velocity,

    springForceAmount,

    airFrictionAmount,

    gravityConstant;

​

function setup() {

  createCanvas(720, 405);

  anchor = createVector(width / 2, height / 2);

  bob = createVector(0, 0);

  velocity = createVector(0, 0);

  springForceAmount = 0.02;

  airFrictionAmount = 1.01;

  gravityConstant = 1;

}

​

function draw() {

  background(22);

  strokeWeight(32);

  stroke(127);

  point(anchor);

  strokeWeight(5);

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

  strokeWeight(64);

  stroke(233);

  point(bob);

  velocity.add(p5.Vector.mult(p5.Vector.sub(bob, anchor), -springForceAmount));

  velocity.add(createVector(0, gravityConstant));

  velocity.div(airFrictionAmount);

  if (velocity.mag() > 1)

    bob.add(velocity);

}

​