Question

Two pulses move in opposite directions on a string and are identical in shape and size except that one has a positive displacement of the elements of the string and the other has negative displacement. At the moment the two pulses completely overlap on the string, what happens?

a) The energy associated with the pulses has disappeared.

b) The string is not moving.

c) The string forms a straight line.

d) The pulses have vanished and will not reappear.