For the laminar flow of water over a sphere, the drag coefficient $C_{F}$ is defined as $C_{F}=F/(\rho U^{2} D^{2})$, where $F$ is the drag force, $\rho$ is the fluid density, $U$ is the fluid velocity and $D$ is the diameter of the sphere. The density of water is $1000 kg/m^{3}$. When the diameter of the sphere is $100$ mm and the fluid velocity is $2$ m/s, the drag coefficient is $0.5$. If water now flows over another sphere of diameter $200$ mm under dynamically similar conditions, the drag force (in N) on this sphere is ________.
