[tex]Dane:\\m = 7 \ kg\\v = 27\frac{km}{h} = 27:3,6\frac{m}{s} = 7,5\frac{m}{s}\\h = 1,2 \ km = 1 \ 200 \ m\\g = 10\frac{m}{s^{2}}=10\frac{N}{kg}\\Szukane:\\E_{m} = ?\\\\Rozwiazanie\\\\E_{m} = E_{p}+E_{k}[/tex]
[tex]E_{p} = mgh = 7 \ kg\cdot10\frac{N}{kg}\cdot1200 \ m = 84 \ 000 \ J\\\\E_{k} = \frac{1}{2}mv^{2} = \frac{1}{2}\cdot7 \ kg\cdot(7,5\frac{m}{s})^{2}} = 196,875 \ J\\\\E_{m} = 84000 \ J = 196,875 \ J\\\\\boxed{E_{m} = 84 \ 196,875 \ J \approx 84 \ 000,9 \ J}[/tex]
