[tex]dane:\\m = 57 \ kg\\E_{p} = 20 \ kJ = 20 \ 000 \ J\\g = 10\frac{N}{kg}\\szukane:\\h = ?\\\\E_{p} = mgh \ \ /:mg\\\\h = \frac{E_{p}}{m\cdot g}\\\\h = \frac{20 \ 000 \ J}{57 \ kg\cdot10\frac{N}{kg}} = \frac{20 \ 000 \ N\cdot m}{570 \ N}\\\\h \approx35 \ m[/tex]