$${F_{\text{ü}} = mvg = \rho_wVg \\ = (1,024 \times 10^3\, \mathrm{kg/m^3})(2,50 \times 10^{-2}\, \mathrm{m}^3)(9,8 \mathrm{m/s^2}) \\ = 2,509 \times 10^2\, \mathrm{N}}$$