[latex]Dane:\t_1=5min= 300s\v_1=30 frac{km}{h} = frac{30000m}{3600s}=8,3(3)frac{m}{s} \t_2=10min=600s\v_2=20 frac{km}{h} = frac{20000m}{3600s}=5,5(5) frac{m}{s} \\Szukane :\v_s_r = ? \\Rozwiazanie :\v_s_r = frac{s_1+s_2}{t_1+t_2}\\v = frac{s}{t} \s = vt\\s_1=300*8,3(3)=2500 m \s_2=600*5,5(5)=3333,3(3) m \\v_s_r = frac{2500+3333,3(3)}{300+600}\\v_s_r = 6,48 frac{m}{s} [/latex]
[latex]dane:\v_1 = 30frac{km}{h}\t_1 = 5 min = frac{1}{20}h\v_2 = 20frac{km}{k}\t_1 10 min = frac{1}{6}h\szukane:\v_{sr} = ?[/latex] [latex]v_{sr} = frac{s_{c}}{t_{c}}\\s = v*t\s_{c} = s_1+s_2 = v_1*t_1+v_2*t_2 = 30*frac{1}{20}+20*frac{1}{6} = frac{3}{2}+frac{10}{3} = frac{29}{6} km\\t=t_1+t_2 = frac{1}{20}+frac{1}{6} = frac{3}{60}+frac{10}{60} = frac{13}{60} h[/latex] [latex]v_{sr} = frac{29}{6}km:frac{13}{60}h = frac{29}{6}*frac{60}{13} frac{km}{h}=frac{290}{13} frac{km}{h}\\v_{sr} = 22,3frac{km}{h}[/latex]
