John Melody

Hello! Please help me understand the scientific article written by P. Mason. I can't figure out what exactly the u_lambda speed means. On what basis did the integral appear in it? I need the retraction rate of the rubber band during the retraction process. Is that her? Is this the speed of the end of the tape retraction in the process? Or does it mean something else? I need to get the rate of retraction of the end, I don't understand if this is it or if I need to express something else. And why does it depend through an integral on the extent to which the wave has passed or what?

Hello! There was a question about the maximum stretching of the rubber band. For example, the Oxford Textbook provides a graph attached below. Can someone share if there is a more detailed schedule? Does the fluidity begin there? Or is it just tearing up? What is the stretching limit? And can we say that tga with line is Young's module at a given tension?