[tex]dane:\\s_{c} = 100 \ km\\s_1 = s_2 = \frac{1}{2}s_{c} = \frac{1}{2}\cdot100 \ km = 50 \ km\\v_1 = 50\frac{km}{h}\\v_2 = 80\frac{km}{h}\\szukane:\\v_{sr} = ?\\\\Rozwiazanie\\\\v_{sr} = \frac{s_{c}}{t_{c}}\\\\t = \frac{s}{v}\\\\t_{c} = t_1 + t_2 = \frac{s_1}{v_1} + \frac{s_2}{v_2} = \frac{50 \ km}{50\frac{km}{h}}+\frac{50 \ km}{80\frac{km}{h}} = 1 \ h + 0,625 \ h = 1,625 \ h\\\\v_{sr} = \frac{100 \ km}{1,625 \ h} \approx61,54\frac{km}{h}[/tex]
