[tex]dane:\\m = 3,2 \ kg\\v = 72\frac{km}{h} = 72\cdot\frac{1000 \ m}{3600 \ s} = 20\frac{m}{s}\\szukane:\\E_{k} = ?\\\\E_{k} = \frac{1}{2}mv^{2}}\\\\E_{k} = \frac{1}{2}\cdot3,2 \ kg\cdot(20\frac{m}{s})^{2} = 1,6 \ kg\cdot400\frac{m^{2}}{s^{2}}}\\\\E_{k} = 640 \ J[/tex]
