3
\begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{ffefbc81-402f-4048-8741-23c8bae30d5a-2_231_485_1238_486}
\captionsetup{labelformat=empty}
\caption{Fig. 1}
\end{figure}
\begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{ffefbc81-402f-4048-8741-23c8bae30d5a-2_206_485_1263_1174}
\captionsetup{labelformat=empty}
\caption{Fig. 2}
\end{figure}
A block of weight 7.5 N is at rest on a plane which is inclined to the horizontal at angle \(\alpha\), where \(\tan \alpha = \frac { 7 } { 24 }\). The coefficient of friction between the block and the plane is \(\mu\). A force of magnitude 7.2 N acting parallel to a line of greatest slope is applied to the block. When the force acts up the plane (see Fig. 1) the block remains at rest.
- Show that \(\mu \geqslant \frac { 17 } { 24 }\).
When the force acts down the plane (see Fig. 2) the block slides downwards.
- Show that \(\mu < \frac { 31 } { 24 }\).