Problem 1.5

Two particles, 1 and $2,$ move with constant velocities $v_{1}$ and $v_{2}$ . At the initial moment their radius vectors are equal to $r_{1}$ and $r_{2}$ . How must these four vectors be interrelated for the particles to collide?

Reveal Answer

\left(\mathbf{r}_{1}-\mathbf{r}_{2}\right) /\left|\mathbf{r}_{1}-\mathbf{r}_{2}\right|=\left(\mathbf{v}_{2}-\mathbf{v}_{1}\right) /\left|\mathbf{v}_{2}-\mathbf{v}_{1}\right|

Kinematics