1.
[tex]Dane:\\m = 0,9 \ kg\\h = 1 \ m\\g = 10\frac{N}{kg}\\Szukane:\\E_{p} = ?\\\\Rozwiazanie\\\\E_{p} = mgh\\\\E_{p} = 0,9 \ kg\cdot10\frac{N}{kg}\cdot 1 \ m\\\\\boxed{E_{p} = 9 \ J}[/tex]
2.
[tex]Dane:\\m = 5 \ kg\\v = 20\frac{m}{s}\\Szukane:\\E_{k} = ?\\\\Rozwiazanie\\\\E_{k} = \frac{mv^{2}}{2}\\\\E_{k} = \frac{5 \ kg\cdot(20\frac{m}{s})^{2}}{2}\\\\\boxed{E_{k} = 1000 \ J = 1 \ kJ}\\\\(1 \ kJ = 1000 \ J)[/tex]
3.
[tex]Dane:\\h = 2 \ m\\E_{p} = 48 \ J\\g = 10\frac{N}{kg}\\Szukane:\\m = ?\\\\Rozwiazanie\\\\E_{p} = mgh \ \ \ |:gh\\\\m = \frac{E_{p}}{gh}\\\\m = \frac{48 \ J}{10\frac{N}{kg}\cdot2 \ m} = \frac{48 \ N\cdot m}{20\frac{N\cdot m}{kg}}\\\\\boxed{m = 2,4 \ kg}[/tex]