일반물리학 1 — Motion in Two and Three Dimensions: Problem 7

7 In a particle accelerator, the position vector of a particle is initially estimated as \(\vec{r} = 6.0\hat{i} - 7.0\hat{j} + 3.0\hat{k}\) and after 10 s, it is estimated to be \(\vec{r} = -3.0\hat{i} + 9.0\hat{j} - 3.0\hat{k}\), all in meters. In unit vector notation, what is the average velocity of the particle?