[tex]dane:\\F = 20 \ N\\v_1 = 2\frac{m}{s}\\t = 5 \ s\\v_2 = 15\frac{m}{s}\\szukane:\\m = ?\\\\Rozwiazanie\\\\a = \frac{\Delta v}{t} = \frac{v_2-v_1}{t} = \frac{(15-2)\frac{m}{s}}{5 \ s} = \frac{13\frac{m}{s}}{5 \ s} = 2,6\frac{m}{s^{2}}\\\\a = \frac{F}{m} \ \ \rightarrow \ \ m = \frac{F}{a}\\\\m =\frac{20 \ kg\cdot\frac{m}{s^{2}}}{2,6\frac{m}{s^{2}}} \approx7,7 \ kg[/tex]
