A crate of mass 10 kg rests on a rough horizontal floor. The coefficient of friction is 0.4. A horizontal force of 15 N is applied to the crate, but the crate remains at rest. Take g=9.8g=9.8g=9.8 m s−2^{-2}−2.
Find the greatest possible friction force.
Find the actual friction force.
Explain why the actual friction force is not equal to μR\mu RμR.
136 exam-style questions on CCEA A Level Maths 2.3 Forces and Newton's laws, covering 2.3.1 Forces and Newton's laws, 2.3.2 Forces and Newton's laws, 2.3.3 Forces and Newton's laws, 2.3.4 Forces and Newton's laws, 2.3.5 Forces and Newton's laws, 2.3.6 Forces and Newton's laws, 2.3.7 Forces and Newton's laws, 2.3.8 Forces and Newton's laws, 2.3.9 Forces and Newton's laws, 2.3.10 Forces and Newton's laws, 2.3.11 Forces and Newton's laws, 2.3.12 Forces and Newton's laws, and 2.3 Forces and Newton's laws. Each one has a worked solution and a mark scheme showing where the marks go.