[tex]Dane:\\v_{o} =0\\f_{z}= 2 \ kHz\\f = 2,1 \ kHz\\v = 340\frac{m}{s}\\Szukane:\\v_{z} = ?\\\\Rozwiazanie\\\\f = f_{z}\cdot\frac{v}{v-v_{z}}\\\\f(v-v_{z}) = f_{z}\cdot v\\\\fv-f_{v_{z} }= f_{z}v\\\\fv_{z} = fv-f_{z}v}\\\\fv_{z} = v(f-f_{z}) \ \ /:f\\\\v_{z} =v\cdot\frac{f-f_{z}}{f}\\\\v_{z} = 340\frac{m}{s}\cdot\frac{2,1 \ kHz - 2 \ kHz}{2 \ kHz}\\\\\boxed{v_{z} = 17\frac{m}{s}}[/tex]
Odp. Źródło zbliża się z prędkością 17 m/s.
