[tex]Dane:\\v_{o} = 0\\h = 100 \ m\\g = 10\frac{m}{s^{2}}\\Szukane:\\t = ?\\\\Rozwiazanie\\\\h = \frac{gt^{2}}{2} \ \ |\cdot2\\\\gt^{2} = 2h \ \ /:g\\\\t^{2} = \frac{2h}{g} \ \ |\sqrt{}\\\\t = \sqrt{\frac{2h}{g}}\\\\t = \sqrt{\frac{2\cdot100 \ m}{10\frac{m}{s^{2}}}} =\sqrt{20 \ s^{2}} = 2\sqrt{5} \ s\\\\\boxed{t \approx4,5 \ s}[/tex]
