[tex]Dane:\\m = 50 \ kg\\v_{o} = 0\\t = 10 \ s\\v = 21,6\frac{km}{h} = 21,6\cdot\frac{1000 \ m}{3600 \ s} = 6\frac{m}{s}\\Szukane:\\F = ?\\\\\\\underline{F = m\cdot a}\\\\ale \ \ a = \frac{\Delta v}{t} = \frac{v}{t} = \frac{6 \ m}{10 \ s} = 0,6\frac{m}{s^{2}}\\\\F = 50 \ kg\cdot0,6\frac{m}{s^{2}}\\\\\boxed{F = 30 \ N}[/tex]