Đáp án:
\(\begin{array}{l}
a.\\
k = N/m\\
b.\\
{W_t} = \frac{5}{{14}}J\\
c.\\
A = \frac{{27}}{{70}}J
\end{array}\)
Giải thích các bước giải:
\(\begin{array}{l}
a.\\
{F_{dh}} = k\Delta l\\
k = \frac{{{F_{dh}}}}{{\Delta l}} = \frac{{10}}{{0,035}} = \frac{{2000}}{7}N/m\\
b.\\
{W_t} = \frac{1}{2}k\Delta {l^2} = \frac{1}{2}.\frac{{2000}}{7}.0,{05^2} = \frac{5}{{14}}J\\
c.\\
A = \frac{1}{2}k(\Delta l{'^2} - \Delta {l^2}) = \frac{1}{2}.\frac{{2000}}{7}(0,{06^2} - 0,{03^2}) = \frac{{27}}{{70}}J
\end{array}\)