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B Can someone explain to me the work equation for springs?

  1. Apr 2, 2016 #1
    I need to find the work done with springs but I don't understand this equation too well, can someone help me know what are each variable and how to find each of them?

    WH - fF*d = ΔK + ΔUs + ΔUg?

    I know that "WH" is the work done by the hand and that "fF*d" is force of friction * displacement, but what I don't understand is what are "ΔK", "ΔUs", and "ΔUg"?
  2. jcsd
  3. Apr 2, 2016 #2

    Simon Bridge

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    A capital delta means "change in" whatever follows.
    K = kinetic energy
    U = potential energy - in this case it is the energy stored in the spring (subscript s) or in gravity (subscript g).

    Note: fF is the force of friction, fF*d is the work done moving a distance d against friction using the definition of work as W=Fd. (The "*" is sometimes used for multiplication.)

    It basically just means that work is equal to the change in energy.
    I'm guessing the spring in question is oriented vertically and has a mass on the end of it.
  4. Apr 2, 2016 #3
    pl. give the background of this relation i.e. whether you are raising a body by using a spring or you are moving a body on the surface by working with your hand etc
    otherwise we can apply only common sense logic of using the notations in physics;
    for example- K and U used for kinetic energy and potential energy in physics-
    so change in K- May denote change in kinetic energy
    change in Us may stand for spring energy -the potential energy of the spring by compression/extension.
    change in Ug may stand for change in gravitational potential energy.
    your equation is a energy -work relation and you are taking the work done in overcoming the frictional forces.
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