"UPDATE" could not be called as a function

this is the update function

this.UPDATE = function()  {     
    this.vel.add(this.acc);     
    this.pos.add(this.vel);     
    this.acc.mult(0); 
    }

this is where it is called

function draw() {
    background(0);
    rocket.UPDATE();
    rocket.render();
}

the error in the non-p5.js console says that UPDATE is not a function

this is the whole code

function Rocket() {
    this.pos = createVector(width/2, height);
    this.vel = createVector(0, -1);
    this.acc = createVector();
    this.applyForce = function(force) {
        this.acc.add(force);
    }
}

this.UPDATE = function()  {
    this.vel.add(this.acc);
    this.pos.add(this.vel);
    this.acc.mult(0);
}

this.render = function(){
    push();
    translate(this.pos.x, this.pos.y);
    rotate(this.vel.heading()); 
    rectMode(CENTER);
    Rect(0,0, 50, 10);
    Pop();
}

function setup() {
    createCanvas(400, 300)
    rocket = new Rocket();
}
function draw() {
    background(0);
    rocket.UPDATE();
    rocket.render();
}

i was expecting a rectangle to start moving upwards from the bottom of the screen. i am following a coding challenge by the coding train to do this.

>Solution :

UPDATE and render must be set in the scope of Rocket, but not in the global scope:

function Rocket() {
    this.pos = createVector(width/2, height);
    this.vel = createVector(0, -1);
    this.acc = createVector();
    this.applyForce = function(force) {
        this.acc.add(force);
    }
  
    this.UPDATE = function()  {
        this.vel.add(this.acc);
        this.pos.add(this.vel);
        this.acc.mult(0);
    }

    this.render = function(){
        push();
        translate(this.pos.x, this.pos.y);
        rotate(this.vel.heading()); 
        rectMode(CENTER);
        rect(0,0, 50, 10);
        pop();
    }
}

function setup() {
    createCanvas(400, 300)
    rocket = new Rocket();
}
function draw() {
    background(0);
    rocket.UPDATE();
    rocket.render();
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/1.5.0/p5.min.js"></script>