Q: Two particle P and Q are moving in gravity free space with their respective velocities $V_P = -\hat{i} + 2\hat{j} -2\hat{i}$ ms^{-1} and $V_Q = -4\hat{i} + 2\hat{j} + 3\hat{k}$ ms^{-1}. At t = t_{o} , the separation between them is minimum. Find the value of 10 t_{o} .

**Ans.** **5**