jak obliczyć gęstość drutu, jeden metr waży 0,025 kg średnica to 2 mm?

[latex]dane:\m = 0,025 kg = 25 g\d = 2 mm = 0,2 cm\h = 1 m = 100 cm\szukane:\d = ?[/latex] [latex]V = S*h = pi (frac{d}{2})^{2}*h = 3,14*(frac{0,2cm}{2})^{2}*100cm = 3,14 cm^{3}\\d = frac{m}{V}\\d = frac{25g}{3,14m^{3}} \\d approx7,96frac{g}{cm^{3}} = 7,96*frac{0,001kg}{0,000001m^{3}} = 7 960frac{kg}{m^{3}}[/latex]