Đáp án:
\(\left\{ \begin{array}{l}
{l_0} = 0,21\left( m \right)\\
k = 50\left( {N/m} \right)
\end{array} \right.\)
Giải thích các bước giải:
ta có
\(\left\{ \begin{array}{l}
{l_1} = {l_0} + \frac{{{m_1}g}}{k}\\
{l_2} = {l_0} + \frac{{{m_2}g}}{k}
\end{array} \right. \Rightarrow \left\{ \begin{array}{l}
0,25 = {l_0} + \frac{{0,2.10}}{k}\\
0,27 = {l_0} + \frac{{0,3.10}}{k}
\end{array} \right. \Rightarrow \left\{ \begin{array}{l}
{l_0} = 0,21\\
\frac{1}{k} = \frac{1}{{50}}
\end{array} \right. \Rightarrow \left\{ \begin{array}{l}
{l_0} = 0,21\left( m \right)\\
k = 50\left( {N/m} \right)
\end{array} \right.\)