Two wave pulses are traveling toward each other on a string, as shown below. Which of the following representations correctly shows the string as the two pulses overlap?

Video Transcript

This is College Physics Answers with Shaun Dychko. Two wave pulses are traveling towards each other and the question is asking which of these pictures represents what will happen when the pulses are on top of each other—they are overlapping— and if we grab one of the pulses and move it over to where the other pulse is when they overlap, this is what the overlap will look like and right now ignore this picture here. So this is what the overlap will look like here in terms of the two different pulses and they will add together in such a way that, you know, the maximally negative part of the red pulse will coincide with the maximum positive part of the blue pulse and they will add to make zero and then, you know, this zero plus zero makes zero here and then the nodes are all... well, I don't suppose they are nodes but anyway these points where they are zero are all going to just be zero still and so the maxima work out to zero as well and then everything in between is going to work out to zero too so this is negative some number and this is positive the same amount and that will add to make zero as well so the answer is (c)— it will just be a straight line while the pulses are overlapping— and then afterwards, the pulses will continue on and then you will still see them again they are not like destroyed, they are just... adding to make zero at this particular moment in time when they overlap and then they will continue on to the right and to the left afterwards.