[tex]\displaystyle Se~da:\\ \\
V=500l=0,5m^3\\ \\
\rho=800\frac{kg}{m^3}\\ \\
pe=10\%\Rightarrow \eta=90\%=0,9\\ \\
m_u=?kg\\ \\ \\
Formule:\\ \\
\eta=\frac{m_u}{m_t}\\ \\
\eta=\frac{m_u}{V\times \rho}\\ \\
m_u=\eta\times V\times\rho\\ \\ \\
Calcule:\\ \\
m_u=0,9\times 0,5\times 800=360kg
[/tex]
