With distances measured in nm and velocity measured in knots, 3 ships $A,B,C$ are observed from a coast guard station. At noon they have the following position and vectors relative to the station.
$\vec{r_A}=-\mathbf i+\mathbf j$ and $\vec{v_A}=\mathbf i+\mathbf j$
$\vec{r_B}=-3\mathbf i+4\mathbf j$ and $ \vec{v_B}=2\mathbf j$
$\vec{r_C}=9\mathbf i+4\mathbf j$ and $\vec{v_C}=-6\mathbf i+2\mathbf j$
Find the position vector of each ship after an hour. Prove that if the ship continues with the same velocity, two of them will collide. Find the time when this happens.
I've tried to understand the question, but I have not.