A two-dimensional, unsteady velocity field is given by

\[ u=5 x(1+t) \quad \text { and } \quad v=5 y(-1+t) \]

where \(u\) is the \(x\)-velocity component and \(v\) the \(y\)-velocity component. Find \(x(t)\) and \(y(t)\) if \(x=x_{0}\) and \(y=y_{0}\) at \(t=0\). Do the velocity components represent an Eulerian description or a Lagrangian description?