[tex]\rho_c=7 \ 800 \ kg/m^3 \\ l_c=10 \ cm=0,1 \ m \\ g=10 \ N/kg \\ \rho_l=1 \ 000 \ kg/m^3 \\ \boxed{p_1-?} \\ \boxed{p_2-?} \\ \bold{Rezolvare:} \\ \boxed{p= \frac{F_n}{S} } \\ \boxed{\rho= \frac{m}{V} } \\ p_1= \frac{F_{n1}}{S} \\ p_2=\frac{F_{n2}}{S}\\ F_{n1}=G_c=m_c \cdot g \\ m=\rho_c \cdot V_c \\ V_c=l_c^3 =(0,1 \ m)^3 =0,001 \ m^3 \\ m_c=7 \ 800 \ kg/m^3 \cdot 0,001 \ m^3=7,8 \ kg \\ F_{n1}=G_c=7,8 \ kg \cdot 10 \ N/kg =78 \ N \\ S=l_c^2 =(0,1 \ m)^2=0,01 \ m^2 [/tex]
[tex]p_1= \frac{78 \ N}{0,01 \ m^2} \\ \Rightarrow \boxed{p_1=7 \ 800 \ Pa} ; \\ F_{n2}=F_{n_1}-F_A \\ F_A=\rho_l \cdot V_{c} \cdot g =1 \ 000 \ kg/m^3 \cdot 0,001 \ m^3 \cdot 10 \ N/kg=10 \ N \\ F_{n2}=78 \ N-10 \ N=68 \ N \\ p_2=\frac{68 \ N}{0,01 \ m^2} \\ \Rightarrow \boxed{p_2=6 \ 800 \ Pa}.[/tex]
