[tex]m=500 \ g=0,5 \ kg \\ \Delta l=0,2 \ m \\ g=10 \ N/kg \\ \boxed{F_e-?} \\ \boxed{k-?} \\ \bold{Rezolvare:} \\ \boxed{k= \frac{F_e}{\Delta l} }\\ F_e=G=m \cdot g \\ F_e=G=0,5 \ kg \cdot 10 \ N/kg \\ \Rightarrow \boxed{F_e=5 \ N} \\ k= \frac{5 \ N}{0,2 \ m} \\ \Rightarrow \boxed{k=25 \ N/m} [/tex]
