Originally Posted By: Bill S.
Are you not overlooking the fact that the spring behaves as an elastic solid only for a finite period of time, albeit a long time? Eventually it will behave as a plastic solid. Its molecules will re-arrange themselves, with


I think you're confusing stored energy with continually spent energy. Stored energy can just stay there till it leaks away as you suggested. When it does leak away it's not being used to apply the force, it's just wasted as heat.

People and animals aren't very good at storing elastic energy in our muscles. We tend to consume energy just holding something still against a force. But that's only because we're not designed for that purpose.