A brick of weight 10 N lies on a rough plane inclined at an angle of 30° 30°\,30° to the horizontal. A force of magnitude 12 N acts on the brick up a line of greatest slope. The brick is in equilibrium, on the point of slipping up the plane.
Find the coefficient of friction between the brick and the plane.
The 12 N force is now removed. Determine whether or not the brick moves.
139 exam-style questions on AQA A Level Maths 3.3 R: Forces and Newton's laws, covering 3.3.1 Concept of a force and Newton's first law, 3.3.2 Newton's second law, 3.3.3 Weight and motion under gravity, 3.3.4 Newton's third law and equilibrium, 3.3.5 Addition of forces and resultants (A-level only), and 3.3.6 Friction (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.