MovieClip.prototype.getSpeed = function() {
    this.momento = new Date();
    this.t2 = this.momento.getTime();
    if (!this.t1) {
        this.t1 = this.momento.getTime();
    }
    this.t = this.t2-this.t1;
    this.t1 = this.t2;
    //
    this.dx2 = this._x;
    this.dy2 = this._y;
    if (!this.dx1 || !this.dy1) {
        this.dx1 = this.dx2;
        this.dy1 = this.dy2;
    }
    this.dx = Math.abs(this.dx2-this.dx1);
    this.dy = Math.abs(this.dy2-this.dy1);
    this.d = Math.sqrt(this.dx*this.dx+this.dy*this.dy);
    this.dx1 = this.dx2;
    this.dy1 = this.dy2;
    //
    this.v = Math.ceil(this.d/this.t*10);
    return this.v;
};
//Uso
obj.onPress = function() {
    startDrag(this);
    this.onEnterFrame = function() {
        this.barra_mc._yscale = this.getSpeed();
    };
};
obj.onRelease = mc.onReleaseOutside=function () {
    stopDrag();
    delete this.onEnterFrame;
};