OpenStax College Physics for AP® Courses, Chapter 17, Problem 7 (Test Prep for AP® Courses)

This is College Physics Answers with Shaun Dychko. We are going to demonstrate that when wave pulses encounter each other along a rope, they do not reflect off of each other but instead they go through each other. And I would demonstrate that by creating two pulses of different amplitudes going towards each other. This would be amplitude B for big and amplitude S for small. And at some time later, this time axis is vertically down here. This picture is sometime later, we will have the two pulses in the same place and they will add together. This is the Superposition Principle that the amplitudes add together when they are on the same place. And so this pulse has an amplitude of the sum of the big and small amplitudes. And then some time later, we will see that the big pulse is continuing to move to the right by itself and then the small is continuing to move to the left by itself. And this is what proves that the pulses go through each other and do not reflect off of each other, because this big pulse is continuing on its way to the right as it always has been unaffected by the fact that it encountered this small pulse here. And if the two pulses were reflected off of each other, the third picture we should see would be like this, with this being the big one and this being the small one. But we do not see that. And so we have shown that they are not reflected, but instead they go through each other.