In this question use g=9.8g = 9.8g=9.8 m s−2^{-2}−2.
A box of mass 20 kg is pulled up a rough plane inclined at an angle of 15° 15°\,15° to the horizontal by a force of magnitude 120 N acting up a line of greatest slope.
The coefficient of friction between the box and the plane is 0.3.
Find the acceleration of the box.
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.