[tex]F_1=10 \ N \\ \Delta l_1=4 \ cm=0,04 \ m \\ F_2=12 \ N \\ \boxed{\Delta l_2-?} \\ \bold{Rezolvare:} \\ \boxed{k= \frac{F_e}{\Delta l} } \Rightarrow \Delta l_2= \frac{F_2}{k} \\ k= \frac{F_1}{\Delta l} = \frac{10 \ N}{0,04 \ m} \\ k=250 \ N/m \\ \Delta l_2= \frac{12 \ N}{250 \ N/m} \\ \Rightarrow \boxed{\Delta l_2=0,048 \ m=\boxed{48 \ cm}}[/tex]
