Re: [Phys-l] workable versus unworkable energy

["John Clement" <clement@hal-pc.org>]

While this is technically true, it is confusing as heck to students.  They
need to first see energy as something "like" a substance that can be
transferred from one place to another.  So the first model of energy
presented to the students needs to emphasize the substance like nature,
which then makes conservation reasonable.  However with experience and more
physics courses a more mature understanding can be developed.  Any attempt
to define it initially as a property of a system will most probably block
acquisition of conservation reasoning.

I totally agree that the words expended and consumed are unfortunate because
they can imply the creation of energy rather than its transfer, but they can
be used among experts who understand the context without fear of
misunderstanding.  But they should not be used with students and the general
public.

John M. Clement
Houston, TX

> Energy, what ever its definition, is not a substance,  a system's
> kinetic energy can not be "expended,"  Nor can energy be "consumed".
> Energy is a property of a system as is its color.  Maybe a string
> theorist will disagree.