[tex]Dane:\\m = 2 \ t = 2 \ 000 \ kg\\v = 72\frac{km}{h} = 72:3,6\frac{m}{s} = 20\frac{m}{s}\\Szukane:\\E_{k} = ?\\\\Rozwiazanie\\\\E_{k} = \frac{1}{2}mv^{2}\\\\E_{k} = \frac{1}{2}\cdot2000 \ kg\cdot(20\frac{m}{s})^{2}}=1000 \ kg\cdot400\frac{m^{2}}{s^{2}}\\\\\boxed{E_{k} = 400 \ 000 \ J = 400 \ kJ}\\\\(1 \ kJ = 1000 \ J)[/tex]
