There is a question involving a simple land rover that can be controlled to go a certain distance. It is two pop bottles connected spout to spout and attached around the middle is a metal tape measure which one would roll up and then let go for the rover to move. I have to explain the mechanics of a spring for this question and how the tape measure acts as a spring. I know that since it's metal, it always wants to be straight so that causes it to move forward and unravel, but it's the rest I don't understand. Would someone be able to explain it to me?