Cheap but not cheerful
I mentioned a few posts back that I was waiting for the arrival of 36 mini slinkies so I could hang them off the ceiling and make a wave by setting them in motion one after the other. Today they arrived nicely packaged and brightly coloured each with a little smiley face printed on the side. I put them in my work bag so I could play with them if the chance arose and arose it did. My first years were doing a the conducting paper practical and were getting on nicely so I thought I'd hang a couple of slinkies. They don't stretch much under their own weight so I attached a rubber ball to each then hung them off the door. It very soon became apparent that these will not do at all. As you can see from the photo their extension under equal force was vastly different which meant their frequency of oscillation will not be the same. Well at least their smiley faces were stretched out, not so happy now then. By the way, notice how engrossed my students are, they thought nothing of the fact that I suddenly decided to hang 3 slinkies from the door.
I of course had to try to make a simulation to see what it was supposed to look like but as you can see below simulations sometimes don't work either.
