[tex]Dan:\\V = 40 \ cm^{3}=0,00004 \ m^{3}\\d = 0,79\frac{g}{cm^{3}} = 790\frac{kg}{m^{3}}\\g = 10\frac{N}{kg}\\Szukane:\\F_{w} = ?\\\\F_{w} = d\cdot g\cdot V\\\\F_{w} = 790\frac{kg}{m^{3}}\cdot10\frac{N}{kg}\cdot0,00004 \ m^{3}}\\\\\boxed{F_{w} = 0,316 \ N}[/tex]
