A rigid rod $(AB)$ of length $L=\sqrt{2} \: m$ is undergoing translational as well as rotational motion in the $x-y$ plane (see the figure). The point $A$ has the velocity $V_1=\hat{i}+2\hat{j} \: m/s$. The end B is constrained to move only along the $x$ direction.

The magnitude of the velocity $V_2$ (in $m/s$) at the end B is __________