Chapter 4, Problem 14P

A proton initially has $\stackrel{\to }{v}=4.0\hat{i}-2.0\hat{j}+3.0\hat{k}$ and then 4.0 s later has $\stackrel{\to }{v}=-2.0\hat{i}-2.0\hat{j}+5.0\hat{k}$ (in meters per second). For that 4.0 s, what are (a) the proton’s average acceleration ${\stackrel{\to }{a}}_{avg,}$ in unit-vector notation, (b) the magnitude of ${\stackrel{\to }{a}}_{avg,}$ and (c) the angle between ${\stackrel{\to }{a}}_{avg,}$ and the positive direction of the x axis?