9709 P41 - Nov 2011 - Q5
3990
A block of mass 2 kg is at rest on a horizontal floor. The coefficient of friction between the block and the floor is \(\mu\). A force of magnitude 12 N acts on the block at an angle \(\alpha\) to the horizontal, where \(\tan \alpha = \frac{3}{4}\). When the applied force acts downwards as in Fig. 1 the block remains at rest.
- Show that \(\mu \geq \frac{6}{17}\).
When the applied force acts upwards as in Fig. 2 the block slides along the floor.
- Find another inequality for \(\mu\).
