I've just been marking some of the reports my students have written about the "resonance in a bucket" experiment. The idea is that they measure the velocity of shallow water waves travelling back and forth across a carton. It reminds me of being in the bath when I was a child. I used to like swishing backwards and forwards making waves travel up and down the bath. The problem was that if you got the right frequency resonance occurred and the bath water spilled over the end of the bath making its way through the kitchen ceiling (In Britain many houses do not have waterproof floors unlike Norway where bath time is much safer). The wave in the carton has a speed that is dependent on the depth of water, once the side is pushed the wave travels across. The question is; "is the speed of the wave dependant on the size of the push?" If the wave was a ball then it would be but since its a wave I don't think it is. Its hard to believe that the speed of the wave is not influenced by the person pushing, it seems like you could make the frequency whatever you like but you can't.