Problem 1.13

Point \(A\) moves uniformly with velocity \(v\) so that the vector \(\mathbf{v}\) is continually "aimed" at point \(B\) which in its turn moves rectilinearly and uniformly with velocity \(u < v\). At the initial moment of time \(\mathbf{v} \perp \mathbf{u}\) and the points are separated by a distance \(l .\) How soon will the points converge?