[tex]Dane:\\\frac{\lambda}{2} = 5 \ cm = 0,05 \ m \ \ \rightarrow \ \ \lambda = 0,0,1 \ m\\v = 36\frac{km}{h} = 36\cdot\frac{1000 \ m}{3600 \ s} =10\frac{m}{s}\\Szukane:\\f = ?\\\\Rozwiazanie\\\\\lambda =\frac{v}{f} \ \ /\cdot f\\\\\lambda f = v \ \ /:\lambda\\\\f = \frac{v}{\lambda}\\\\f = \frac{10\frac{m}{s}}{0,1 \ m}\\\\\boxed{f = 100 \ Hz}[/tex]
