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Re: Is there more than one type of kinetic energy

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  • Re: Is there more than one type of kinetic energy

    Dear all,

    I would to comment on the question raised by Richard Baker and
    maybe adding something to the response by Jon Dingwell. Usually I consider
    the kinetic energy as

    T = int_{\Omega}(|V \cdot V) \rho dx (integral of the square of the
    velocity modulus times
    the density
    times differential of volume)

    That takes into account inhomogeneities and the possibility of deformation.
    Complex media usually presents complex coupling behavior between certain
    more simple decomposition of the
    kinetic energy. When modelling highly inhomogeneous segments in an automatic
    form we can always use the formulation above for discretized domains (like
    in finite element methods).

    Best regards,


    Felix C. G. Santos
    _____________________________________
    Computational Mechanics Group - GMC/UFPE
    Federal University of Pernambuco
    Brazil






    ----- Original Message -----
    From: Richard Baker
    To:
    Sent: Thursday, March 16, 2000 1:47 PM
    Subject: Is there more than one type of kinetic energy


    > In calculating the total amount of work done on the basis of the movements
    > of body segments, during gait for example, it is common (Winter 1979,
    > Pierrynowski 1980, Viswanath 1999) to consider the potential energy, the
    > translational kinetic energy and the rotational kinetic energy. In
    > calculating total work done the translational and rotational energy terms
    > are treated as separate. Is this justified?
    >
    > It is my understanding that there is just one scalar quantity, kinetic
    > energy, and that the translational and rotational "components" are simply
    a
    > means of calculating this total. Given this surely the total kinetic
    energy
    > for each segment should be treated as a single term for the calculation of
    > total work.
    >
    > Whilst we are on this subject, there is at least one series of papers
    which
    > talks of the forward, lateral and vertical components of translational
    > kinetic energy (although the use of the terms does not affect the
    > mathematical analysis). Surely kinetic energy is a scalar and there is no
    > physical meaning to these "components"?
    >
    > Am I right? Right, but overly pedantic? Plain wrong?
    >
    > I'd be interested in anyone's comments.
    >
    > Richard
    >
    > Richard Baker PhD
    > Gait Analysis Service Manager
    > Musgrave Park Hospital, Stockman's Lane, Belfast, Northern Ireland, BT9
    7JB
    > Tel: +44 2890 669501 ext 2155 or 2849
    > Fax: +44 2890 382008
    >
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