Odpowiedź :
Wyjaśnienie:
Ek = 1/2 × m × V^2
m = 2Ek/ V^2
[tex]m = \frac{2 \times 200j}{(10 \frac{m}{s} ){2} } = \frac{400kg \times \frac{ {m}^{2} }{ {s}^{2} } }{100 \frac{ {m}^{2} }{ {s}^{2} } } = 4kg[/tex]
[tex]dane:\\v = 10\frac{m}{s}\\E_{k} = 200 \ J}\\szukane:\\m = ?\\\\Rozwiazanie\\\\E_{k} = \frac{mv^{2}}{2} \ \ /\cdot 2\\\\mv^{2} = 2E_{k} \ \ /:v^{2}\\\\m = \frac{2E_{k}}{v^{2}}\\\\m = \frac{2\cdot200 \ J}{(10\frac{m}{s})^{2}} = \frac{400 \ kg\cdot\frac{m^{2}}{s^{2}}}{100\frac{m^{2}}{s^{2}}}{ = 4 \ kg[/tex]
Odp. Piłka lekarska ma masę m = 4 kg.