[tex]3.\\Dane:\\S = 4 \ dm^{2} = 0,04 \ m^{2}\\p = 5\frac{N}{cm^{2}} = \frac{5 \ N}{0,0001 \ m^{2}}= 50 \ 000 \ \frac{N}{m^{2}}\\Szukane:\\F = ?\\\\\\p = \frac{F}{S} \ \ \rightarrow \ \ F= p\cdot S\\\\F = 50000\frac{N}{m^{2}}\cdot0,04 \ m^{2}\\\\\boxed{F = 2 \ 000 \ N = 2 \ kN}[/tex]
[tex]4.\\Dane:\\F = 3 \ kN = 3 \ 000 \ N\\p = 2 \ kPa = 2 \ 000 \ Pa = 2 \ 000\frac{N}{m^{2}}\\Szukane:\\S = ?\\\\p = \frac{F}{S} \ \ \rightarrow \ \ S = \frac{F}{p}\\\\S = \frac{3000 \ N}{2000\frac{N}{m^{2}}}\\\\\boxed{S = 1,5 \ m^{2}}[/tex]
