[tex]Dane:\\m = 10 \ kg\\p = 400 \ Pa = 400 \ \frac{N}{kg}\\g = 10\frac{N}{kg}\\Szukane:\\S = ?\\a = ?\\\\p = \frac{F}{S} \ \ /\cdot S\\\\p\cdot S = F \ \ /:p\\\\\underline{S = \frac{F}{p}}\\\\ale: \ \ F = m\cdot g = 10 \ kg\cdot10\frac{N}{kg} = 100 \ N\\\\S = \frac{100 \ N}{400\frac{N}{m^{2}}}\\\\\boxed{S = 0,25 \ m^{2}}[/tex]
[tex]S = a^{2}\\\\a^{2} = 0,25 \ m^{2}\\\\a = \sqrt{0,25 \ m^{2}}}\\\\\boxed{a = 0,5 \ m}[/tex]
