An object hangs in equilibrium from a spring, as shown above. The object is then displaced to one of the labeled points X , Y, or Z . Which of the following correctly ranks the elastic potential energyU stored in the spring when the object is at each of the three positions? 6) Us > (U): = Ur) U7P(Ux=Uz) [1)! > U1 3 Us Ur :5 Up: but