161- The figure below shows the variation of the elastic force of three springs as a function of their elongation. If the elastic force $F_e = 30\,\text{N}$ elongates spring $S_2$ by 4 cm, by how many centimeters do the lengths of springs $S_1$ and $S_2$ increase, respectively? [Figure: Graph of $F_e$ vs. $x$ showing three lines $S_1$, $S_2$, $S_3$ with increasing slopes]
[(1)] 3 and 6
[(2)] 6 and 2
[(3)] 8 and 2
[(4)] 9 and 3
\textbf{161-} The figure below shows the variation of the elastic force of three springs as a function of their elongation. If the elastic force $F_e = 30\,\text{N}$ elongates spring $S_2$ by 4 cm, by how many centimeters do the lengths of springs $S_1$ and $S_2$ increase, respectively?
\textit{[Figure: Graph of $F_e$ vs. $x$ showing three lines $S_1$, $S_2$, $S_3$ with increasing slopes]}
\begin{itemize}
\item[(1)] 3 and 6
\item[(2)] 6 and 2
\item[(3)] 8 and 2
\item[(4)] 9 and 3
\end{itemize}
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