Obliczmy najpierw częstotliwość
[tex]f = \frac{1}{T} [/tex]
[tex]f = \frac{1}{2} = 0.5Hz[/tex]
Zamienny
[tex]72 \frac{km}{h} = 72 \times \frac{1000}{3600} = \frac{72000}{3600} = 20 \frac{m}{s} [/tex]
Zatem
[tex] \lambda = \frac{v}{f} [/tex]
[tex] \lambda = \frac{20}{0.5} = 10m[/tex]