The two pulses reflect off the boundaries of the string, and at some later time, they pass through the middle of the string and interfere. Below are six different sequences of snapshots taken as the two pulses meet in the middle of the string. Time increases from top to bottom in each sequence. Which sequence correctly represents the displacement of the string as the pulses interfere?

8.29 two streams containing pyridine and acetic acid at 25°c are mixed and fed into a heat exchanger. due to the heat-of-mixing effect, it is desired to reduce the temperature after mixing to 25°c using a stream of chilled ethylene glycol as indicated in the diagram. calculate the mass flow rate of ethylene glycol needed. the heat capacity of ethylene glycol at these conditions is approximately 2.8 kj/(kg k), and the enthalpy change of mixing (δmixh) is given below.