[问答题]
The two pulses shown in Fixgyo4 bip2ak3(6m;( x skg0ta g. 11– ijcq4a/l*d1h 52 are moving toward each other. (a) Sketch the shape of the string at the moment they directly overlap. (b) Sketch the cjlia4 d/1q h*shape of the string a few moments later. (c) In Fig. 11–36a, at the moment the pulses pass each other, the string is straight. What has happened to the energy at this moment?