\textbf{188.} A pendulum oscillates along the line $MN$ with length $6\,\text{cm}$. If the time it takes to travel from $M'$ to $N'$ is $\frac{1}{2}$ seconds, what is the speed (in cm/s) of the pendulum when passing through point $N'$?
\textit{[Figure: A horizontal line with points M, M$'$, O, N$'$, N marked, and $MM' = N'N = 1.5\,\text{cm}$]}
\begin{itemize}
\item[(1)] $\sqrt{3}\,\pi$
\item[(2)] $\dfrac{\sqrt{3}}{2}\,\pi$
\item[(3)] $\pi$
\item[(4)] $2\pi$
\end{itemize}