Originally Posted by
Mark Rakestraw
Hi Michael. No one is disputing anything you've said above. Moving the weight does "use" energy, but it doesn't make energy disappear, it just converts it. And yes, that statement is counter-intuitive, which is why I think it's interesting. If anyone else is interested in the topic the book "E=mc2: A Biography of the World's Most Famous Equation" by David Bodanis is an easy to read history of man's understanding of physics through the centuries. It includes the evolution of the concepts of the conservation of mass and the conservation of energy and how these principles informed Einstein's famous theory. I read this book a short while ago and was excited to see what looks to me like a "real life" example in this thread. I didn't mean to start an argument and my apologies to the OP,Paul, for what turned out to be a hijacking of his thread.