[tex]\displaystyle Se~da:\\ \\
E=9,8\times 10^4Pa\\ \\
l_0=1m\\ \\
S=10mm^2=0,00001m^2\\ \\
\Delta l=1cm=0,01m\\ \\
F=?mN\\ \\ \\
Formule:\\ \\
E=\frac{F\times l_0}{\Delta l \times S}\\ \\
F=\frac{E\times\Delta l\times S}{l_0}\\ \\ \\
Calcule:\\ \\
F=\frac{9,8\times 10^4\times0,01\times 0,00001}{1}=0,0098N=9,8mN[/tex]
