[tex]\boxed{\bold{4}}. \ a) \ \vec{G} ; \ b) \ F_e; \ c) \ F_f; \ d) \ \vec{P}. \\ \boxed{\bold{5}}. \ \triangle l=2 \ cm=0,02 \ m \\ F_e=1,5 \ N \\ \boxed{k-?} \\ \boxed{G-?} \\ \bold{Rezolvare:} \\ \boxed{k= \frac{F_e}{\triangle l} }\\ k= \frac{1,5 \ N}{0,02 \ m} \\ \Rightarrow \boxed{k=75 \ N/m} \\ G=F_e \\ \Rightarrow \boxed{G=1,5 \ N}. \\ \boxed{\bold{6}}. \ m=100 \ kg \\ g_1=9,8 \ N/kg \\ g_2=1,6 \ N/kg \\ \boxed{G_1-?} \\ \boxed{G_2-?} \\ \bold{Rezolvare:} \\ \boxed{G=m \cdot g}\\ \Rightarrow G_1=m\cdot g_1; \ G_2=m\cdot g_2[/tex]
[tex]G_1=100 \ kg \cdot 9,8 \ N/kg \\ \Rightarrow \boxed{G_1=980 \ N} \\ G_2=100 \ kg \cdot 1,6 \ N/kg \\ \Rightarrow \boxed{G_2=160 \ N}. \\ \boxed{\bold{7}}. \\ k=50 \ N/m \\ F_1=1 \ N \\ m^2=200 \ g=0,2 \ kg \\ g=10 \ N/kg \\ \boxed{\triangle l_1 -? } \\ \boxed{\triangle l_2-?}\\ \bold{Rezolvare:} \\ \boxed{k= \frac{F_e}{\triangle l} } \\ \Rightarrow \triangle l_1= \frac{F_1}{k} \\ \triangle l_1= \frac{1 \ N}{50 \ N/m} \\ \Rghtarrow \boxed{\triangle l_1=0,02 \ m=2 \ cm} \\ \triangle l_2= \frac{F_2}{k} [/tex]
[tex]F_2=G_2=m_2 \cdot g \\ F_2=G_2=0,2 \ kg \cdot 10 \ N/kg \\ F_2=2 \ N \\ \triangle l_2= \frac{2 \ N}{50 \ N/m} \\ \Rightarrow \boxed{\triangle l_2=0,04 \ m=4 \ cm}. \\ \boxed{\bold{8}}. \ a) \ \downarrow; \ b) \ \swarrow; \ c) \ \nearrow.[/tex]
