Setup: A rope is fixed at one end to a wall. You swing the other end up and down once. A wave starts travelling. It moves, hits the wall, then flattens, then is created again underneath (inversed), and then starts travelling back.
Question: The inversion itself makes sense. The wall responds with a force downwards on the rope when the wave in the rope tries to pull the wall upwards to continue (Newtons 3rd law). But why is there a delay?
At the point where the wave is perfectly flat, what is in that exact moment pulling the rope downwards? In that moment the wave is not pushing the wall upwards anymore, so the wall will also not give any force. Or am I wrong? Where to has the energy in the travelling wave been converted which gives it back to the rope in the flattened moment?