work Summary

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work Summary

  • Work
    • is done whenever a force results in a displacement.
      • The component of the force parallel to the displacement is what matters.
    • is the scalar product of force and displacement.

      W = Δs cos θ

    • is the force-displacement path integral.
      W = 
      F · ds
  • Work-Energy Theorem
    • Work is done when the energy of an object changes form (energy transduction).
    • Work is done when energy is transfered from one object to another (energy transfer).
    • Work is a change in energy.
    abbreviated version
    W = ΔE 
     
    algebra version 
    Δs cos θ = ΔE 
     
    calculus version 

    F · ds = ΔE
  • Units
    • The SI unit of work and energy is the joule, named after the English physicist and brewer James Joule (1818–1889).

      [J = Nm = kg m2/s2]

    • The electron volt is an acceptable non SI unit of energy. It is used for some applications in electromagnetism; solid state, atomic, nuclear, and particle physics; and related sciences like biophysics, chemistry, and astronomy. An electron volt is the work done a particle with one elementary charge when it is moved between two points with a potential difference of one volt. It is described in more detail in the section on electric potential (a.k.a. voltage).

      1 eV = (1.6 × 10−16 C)(1 V) = 1.6 × 10−16 J

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