public void add(Force f) {
		double myX = this.getX();
		double hisX = f.getX();
		double myY = this.getY();
		double hisY = f.getY();

		double newX = myX + hisX;
		double newY = myY + hisY;
		this.magnitude = Math.pow(Math.pow(newX, 2) + Math.pow(newY, 2), 0.5);

		if (newX == 0) {
			if (newY > 0) {
				direction = Math.PI/2;
				return;
			}
			if (newY < 0) {
				direction = 3*Math.PI/2;
				return;
			}
		}

		if (newY == 0) {
			if (newX > 0) {
				direction = 0;
				return;
			}
			if (newX < 0) {
				direction = Math.PI;
				return;
			}
		}

		if (newX > 0) {
			direction = Math.atan(newY/newX);
		}
		if (newX < 0) {
			direction = Math.atan(newY/newX) +Math.PI;
		}
	}