constructor(x, w, m, v) {

    this.x = x

    this.w = w

    this.m = m

    this.v = v

  }

  hitWall() {

    return this.x <= 0;

  }

  reverse() {

    this.v *= -1;

  }

  show() {

    rectMode(CORNER)

    rect(this.x, 200 - this.w, this.w)

  }

  update() {

    this.x += this.v

  }

  collide(other) {

    return !(this.x + this.w < other.x || this.x > other.x + other.w);

  }

  bounce(other) {

​

    let sumM = this.m + other.m;

    let newV = ((this.m - other.m) / sumM) * this.v;

    newV += ((2 * other.m) / sumM) * other.v;

    return newV;

  }

}