Incline with Friction
Part of the Mechanics section of Coddy's Physics journey. Lesson 20 of 94.
On a ramp N = mg cos θ, so kinetic friction is fk = μk mg cos θ, along the slope against the sliding. Sliding down, with down the slope positive:
mg sin θ - μk mg cos θ = ma
Sliding down: friction points up the slope, against the sliding.
A box moving up the slope feels friction down the slope, on the same side as gravity's pull.
Challenge
An 8 kg box slides down a 30° ramp. The kinetic friction coefficient is μ = 0.2. Find its acceleration a.
Try it yourself
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
All lessons in Mechanics
1Vectors and Newton's Laws
Right TrianglesWhat is a Vector?Adding VectorsAxes and DirectionsVector ComponentsForces Around UsFriction and TensionNewton's First LawNewton's Second LawNewton's Third LawRecap - Net Force2Friction
What is Friction?Static FrictionKinetic FrictionFriction and Newton's LawsRecap - Sliding Crate3Inclined Planes
Forces on an InclineGravity ComponentsFrictionless InclineIncline with FrictionWill It Slide?Recap - Ramp Challenge6Projectile Motion
Independent AxesHorizontal LaunchLaunch at an AngleRange and Max HeightRecap - Hit the Target9Work and Energy
WorkKinetic EnergyWork-Energy TheoremGravitational PEConservation of EnergyPowerRecap - Roller Coaster12Impulse and Momentum
MomentumImpulseConservation of MomentumElastic CollisionsInelastic CollisionsRecap - Air Track15Simple Harmonic Motion
What is SHM?Mass on a SpringThe PendulumSHM GraphsEnergy in SHMRecap - Oscillator