FrictionEdexcel A-Level Maths: Flashcards

What these 12 flashcards ask

State the friction model.
When is F=\mu R?
A body at rest is pushed by a small force. What is the friction?
What is limiting friction?
What do you find first when a force acts at an angle to the surface?
Rope at \theta above horizontal, tension T: normal reaction?
Condition for a particle to rest on a rough plane at angle \alpha?
Acceleration down a rough slope at \alpha?
Which way does friction act on a particle sliding up a slope?
Deceleration of a body sliding on a rough horizontal surface with no other force?
What happens to friction on the block when the string goes slack?
10 kg box, \mu=0.3: maximum friction?

Exam questions on Friction

A box of mass 10 kg rests on a rough horizontal floor. The coefficient of friction between the box and the floor is 0.3. A horizontal force is applied to the box. Take $g=9.8\ \text{m s}^{-2}$ .
Explain why the friction force in part (a) is 25 N and not $\mu R$ , and state the greatest horizontal force that can be applied without the box moving.2 marks
A particle of mass 5 kg is placed on a rough plane inclined at $20^\circ$ to the horizontal. The coefficient of friction between the particle and the plane is $\mu$ . Take $g=9.8\ \text{m s}^{-2}$ .
The coefficient of friction is now 0.3 and the particle slides down the plane. Find its acceleration.2 marks
A crate of mass 20 kg is pulled along a rough horizontal floor by a light rope inclined at $30^\circ$ above the horizontal. The tension in the rope is 80 N, the crate is moving and the coefficient of friction between the crate and the floor is 0.25. Take $g=9.8\ \text{m s}^{-2}$ .
Find the magnitude of the normal reaction of the floor on the crate and the magnitude of the friction force.3 marks

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).