A proton initially has V = (-5.60)î + (-15.0)ĵ + (4.20)k and then 2.20 s later has V = (-2.90)i + (-15.0)j + (-6.30)k (in meters per second). (a) For that 2.20 s, what is the proton's average acceleration a avg in unit vector notation, (b) in magnitude, and (c) the angle between á avg and the positive direction of the x axis?

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.