[tex]dane:\\v_{o} =0\\h = 8 \ m\\g = 10\frac{m}{s^{2}}\\szukane:\\v = ?\\\\Z \ zasady \ zachwania \ energii\\\\E_{p} = E_{k}\\\\mgh = \frac{mv^{2}}{2} \ \ /\cdot\frac{2}{m}\\\\v^{2} = 2gh\\\\v = \sqrt{2gh} = \sqrt{2\cdot10\frac{m}{s^{2}}\cdot8 \ m}=\sqrt{160\frac{m^{2}}{s^{2}}}=\sqrt{16\cdot10} \ \frac{m}{s} = 4\sqrt{10} \ \frac{m}{s}\\\\v \approx12,65\frac{m}{s}[/tex]
