A package of weight 20 N lies on a rough plane inclined at an angle of 25∘ 25^\circ\,25∘ to the horizontal. A force of 16 newtons acts on the package up the plane and the package is in equilibrium on the point of slipping up the plane.
Find the coefficient of friction between the package and the plane.
The 16 N force is removed. Determine whether or not the package 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.