public void updateVelocity() {
        int cap = this.getCart().getCurrentCapacity();
        if(cap >= 0 && cap < 50)
            this.setVelocity(170);
        else if(cap >= 50 && cap < 100)
            this.setVelocity(150);
        else if(cap >=100 && cap < 150)
            this.setVelocity(120);
        else if(cap >=150 && cap <= 200)
            this.setVelocity(100);
    }