[tex]dane:\\r = 8 \ cm = 0,08 \ m\\n = 120\\t = 1 \ min = 60 \ s\\szukane:\\v = ?\\\\Rozwiazanie\\\\v = 2\pi rf\\\\ale \ \ f = \frac{n}{t} = \frac{120}{60 \ s} = 2 \ Hz\\\\v = 2\cdot3,14\cdot0,08 \ m\cdot2 \ \frac{1}{s}\\\\v = 1,0048 \ \frac{m}{s}\approx 1\frac{m}{s}[/tex]
