s₁ = 6 km V₁ = 12 km/h s₂ = 4 km V₂ = 6 km/h Vśr = ? [latex]V_s_r = frac{s_1 + s_2 }{t_1+ t_2} [/latex] [latex]V_s_r = frac{s_1+ s_2 }{ frac{s_1}{V1 } + frac{s_2}{V_2 } } = frac{s_2+ s_2 }{ frac{s_1V_2 + s_2V_1}{V_2V_2} } = frac{V_1V_2 * ( s_1 + s_2)}{s_1V_2 + s_2 V_1} [/latex] [latex]V_s_r = frac{12 frac{km}{h}* 6 frac{km}{h } * ( 6 km + 4 km)}{6 km* 6 frac{km}{h} + 4 km * 12 frac{km}{h} } = 8,6 frac{km}{h} [/latex] jeżeli ma to byc na poziomie gimnazjum to można dodać prostsze rozwiązanie: t₁ = s₁/V₁ t₁ = 6 km/12 km/h = 0,5 h t₂ = 4 km/6 km/h = 0,67 h Vsr = 6 km + 4 km / 0,5 h + 0,67 h Vsr = 10 km /1,17 h ≈ 8,55 km/h = 8,6 km/h
