\textbf{49.} A horizontal disk rotates about its own vertical axis and two persons A and B sit on the disk respectively at distances of one meter and two meters from the center. Which person has greater centripetal acceleration, and if the speed of the disk gradually increases, which surface will slide sooner? (The surface material is the same.)
\begin{itemize}
\item[(1)] A and A
\item[(2)] B and B
\item[(3)] A and B
\item[(4)] B and A
\end{itemize}
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