[tex]Dane:\\v _{o} = 0\\v = 72\frac{km}{h} = 72\cdot\frac{1000 \ m}{3600 \ s} = 20\frac{m}{s}\\g = 10\frac{m}{s^{2}}\\Szukane:\\t = ?\\\\\\v = g\cdot t \ \ /:g\\\\t = \frac{v}{g}\\\\t = \frac{20\frac{m}{s}}{10\frac{m}{s^{2}}}\\\\\boxed{t = 2 \ s}[/tex]
Odp. Po czasie 2-ch sekund.
