You wish to check your luggage for a flight. However, the scale at the airport is broken. You found a spring that obeys Hooke's Law hanging off the wall. Assume the spring is weightless. You hang a jug of 2 kilogram of water from the spring and observe that the spring stretches beyond its natural length by 5 centimetre. If you hang a 10 kg luggage from the spring, how far does it stretch beyond its natural length? Assume distance is measured in metres.