[tex]Dane:\\s_1 = 40 \ m\\v_1 = 4\frac{m}{s}\\t_2 = 50 \ s\\v_2 = 2\frac{m}{s}\\Szukane:\\v_{sr} = ?\\\\Rozwiazanie\\\\\underline{v_{sr} = \frac{s_{c}}{t_{c}}}\\\\t_1 = \frac{s_1}{v_1} = \frac{40 \ m}{4\frac{m}{s}} = 10 \ s\\\\s_2 = v_2\cdot t_2 = 2\frac{m}{s}\cdot50 \ s =100 \ m\\\\s_{c} = s_1+s_2 = 40 \ m + 100 \ m = 140 \ m\\t_{c} = t_1+t_2 = 10 \ s + 50 \ s = 60 \ s\\\\v_{sr} = \frac{140 \ m}{60 \ s}\\\\\boxed{v_{sr} = 2,3\frac{m}{s}}[/tex]
