FrictionAQA A-Level Maths: Mind map

Exam questions on Friction

1. A box of mass $10$ kg rests on rough horizontal ground. The coefficient of friction between the box and the ground is $0.4$. Take $g=9.8\ \text{m s}^{-2}$.
   A horizontal force of magnitude $30$ N is applied to the box. Find the magnitude of the friction force, justifying your answer.2 marks
2. A block of mass $5$ kg is placed at rest on a rough plane inclined at $20^\circ$ to the horizontal. The coefficient of friction between the block and the plane is $0.5$. Take $g=9.8\ \text{m s}^{-2}$.
   Show that the block does remain at rest.2 marks
3. A crate of mass $20$ kg is pulled from rest along rough horizontal ground by a horizontal rope with tension $90$ N. The coefficient of friction between the crate and the ground is $0.3$. Take $g=9.8\ \text{m s}^{-2}$.
   Find the acceleration of the crate.3 marks