Question

samochod jedzie 10 km z v = 100km/h i 20 km z v= 30km/h oblicz szybksc srednia samochodu

Answer 1

[tex]Dane:\\s_1 = 10 \ km\\v_1 = 100\frac{km}{h}\\s_2 = 20 \ km\\v_2 = 30\frac{km}{h}\\Szukane:\\v_{sr} = ?\\\\Rozwiazanie\\\\v_{sr} = \frac{s_{c}}{t_{c}}\\\\t_{c} = s_1+s_2 = 10 \ km + 20 \ km = 30 \ km\\\\t = \frac{s}{v}\\\\t_{c} = \frac{s_1}{v_1}+\frac{s_2}{v_2} = \frac{10 \ km}{100\frac{km}{h}}+\frac{20 \ km}{30\frac{km}{h}} = \frac{1}{10} \ h + \frac{2}{3}} \ h = \frac{3+20}{30} \ h = \frac{23}{30} \ h[/tex]

[tex]v_{sr} = \frac{30 \ km}{\frac{23}{30} \ h}\\\\\boxed{v_{sr} = 39,13\frac{km}{h}}[/tex]