🧠

Friction

Kinetic Friction

  • Sliding Friction
  • Force of kinetic friction
  • Acts in the opposite direction of a sliding object's velocity
    • Is proportional to the normal force between the two surfaces
      • Not a fundamental law but an experimental relation

Kinetic Friction Equation

  • Ffr=μkFNF_{fr} = \mu_kF_N
    • FfrF_{fr} is the friction force
    • FNF_N is the normal force
    • μk\mu_k is the coefficient of kinetic friction
      • Depends on the nature of the two surfaces
      • Has no units

Static Friction

  • A force parallel to two surfaces
  • Can arise when they are not sliding

Static Friction Equation

  • (Ffr)max=μsFN(F_{fr})_{max} = \mu_sF_N
    • FfrF_{fr} is the friction force
    • FNF_N is the normal force
    • μs\mu_s is the coefficient of static friction
  • FfrμsFNF_{fr} \leq \mu_sF_N

Physics