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Work-energy principle and conservative forces

  1. Apr 17, 2014 #1
    Hi, all there are equation in the pic but I cant understand them. I know work-energy principle which
    is W= F * X (work equals force times way) but I think they are special forms. What concepts
    and topics should I study to understand them?

    Attached Files:

  2. jcsd
  3. Apr 17, 2014 #2


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    Gold Member

    W = F*x is a special case of the integral:

    [tex]W = \int F dx[/tex]

    if F is not dependent on x, then we can write:

    [tex]W = F \int_{x_i}^{x_f} dx[/tex]

    and that's just

    [tex]W = F (x_f - x_i) [/tex]

    The x you use is the distance moved, which is just the difference between the final and initial position, as I have written.

    The equation you show accounts for all forces on a particle and breaks them into conservative and non-conservative forces and assumes the particle is in equilibrium, setting that sum of forces to zero.
  4. Apr 17, 2014 #3
    The text also makes use of the definition of potential energy difference dV in terms of the work done by a conservative force Wc= - dV
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