(3:3) The Wave Equation: Consequences (Walter Lewin, MIT)

[DoctorFastest]

It looked like his string was a spring of some kind. But it works with a normal string, too; it doesn't have to be able to stretch. The only catch is that the string has to be heavy enough that the air resistance is negligible compared to the momentum, and that the string be flexible rather than stiff. In other words, air resistance makes it so this won't work for a piece of thread, and stiffness makes it so that it won't work with a thick cable. But for most strings, a good approximation.

[mirageus]

what kind of string did you use? it looked like it did have some elasticity to it

[GGRSC]

awesome