[tex]Dane:\\m=2,5 \ g = 0,0025 \ kg\\v_{o} = 0\\t = 0,02 \ s\\v = 40\frac{m}{s}\\Szukane:\\F = ?\\\\Rozwiazanie\\\\F = m\cdot a\\\\ale\\\\a = \frac{\Delta v}{t} = \frac{v-v_{o}}{t}=\frac{v}{t} = \frac{40\frac{m}{s}}{0,02 \ s} =2000\frac{m}{s^{2}}\\\\czyli\\\\F = 0,0025 \ kg\cdot2000\frac{m}{s^{2}}\\\\\boxed{F = 5 \ N}[/tex]