7.
[tex]dane:\\S_1 = 30 \ cm^{2}\\S_2 = 3 \ 000 \ cm^{2}\\m_2 = 1000 \ kg\\g = 10\frac{N}{kg}\\szukane:\\F_1 = ?\\\\Rozwiazanie\\\\F_2 = m_2\cdot g = 1000 \ kg\cdot10\frac{N}{kg} = 10 \ 000 \ N\\\\Z \ prawa \ Pascala\\\\\frac{F_1}{S_1} = \frac{F_2}{S_2}\\\\F_1\cdot S_2 = F_2 \cdot S_1 \ \ /:S_2\\\\F_1 = F_2 \cdot\frac{S_1}{S_2}\\\\F_1 = 10 \ 000 \ N\cdot\frac{30 \ cm^{2}}{3000 \ cm^{2}}\\\\\underline{F_1 = 100 \ N}[/tex]
8.
[tex]dane:\\h = 3 \ km = 3 \ 000 \ m\\d = 2r = 20 \ cm\\r = 10 \ cm = 0,1 \ m\\\rho=1030\frac{kg}{m^{3}} \ - \ gestosc \ wody \ slonej\\g = 10\frac{N}{skg}\\szukane:\\F = ?\\\\Rozwiazanie\\\\p = \frac{F}{S} \ \ \rightarrow \ \ F = p\cdot S\\\\\\p = \rho\cdot g\cdot h\\\\p=1030\frac{kg}{m^{3}}\cdot10\frac{N}{kg}\cdot3 000 \ m\\\\p = 30 \ 900 \ 000 \ Pa =309\cdot10^{5} \ Pa[/tex]
[tex]S = \pi r^{2}\\\\S = 3,14\cdot(0,1 \ m)^{2}\\\\S = 0,0314 \ m^{2}\\\\\\F = p\cdot S\\\\F = 309\cdot10^{5} \ Pa\cdot0,0314 \ \ m^{2}}\\\\F = 309\cdot10^{5}\frac{N}{m^{2}}\cdot0,0314 \ m^{2}}\\\\F = 9,7026\cdot10^{5} \ N\\\\\underline{F = 970 \ 260 \ N}[/tex]
