the value of \(m\).
\section*{3.}
\begin{figure}[h]
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\caption{Figure 2}
\includegraphics[alt={},max width=\textwidth]{31c17a67-4fcf-4402-b00e-239ce9f20964-3_241_1202_388_420}
\end{figure}
A plank of wood \(A B\) has mass 10 kg and length 4 m . It rests in a horizontal position on two smooth supports. One support is at the end \(A\). The other is at the point \(C , 0.4 \mathrm {~m}\) from \(B\), as shown in Figure 2. A girl of mass 30 kg stands at \(B\) with the plank in equilibrium. By modelling the plank as a uniform rod and the girl as a particle,