Re: Why work before energy in texts

[John Clement <clement@HAL-PC.ORG>]

I think one can use words without necessarily giving an interpretation.  For
example saying "the amount of work equals the change in kinetic energy" in a
particular situation does not necessarily give an interpretation.  Then
rather than telling the students your conceptual model, it might be better
to ask them what that means to them.  This allows them to construct their
own models and then communicate them.  You could reveal your own model after
their models had been discussed by them.  They will often never form a firm
conceptual model if you hand them one that they do not understand.  Often
they will form a good enough model after discussion that you will not have
to reveal your own model.  By asking rather than telling, you are forcing
them to think more and to develop better thinking skills.

John M. Clement
Houston, TX

> When you correctly use a work-energy theorem (validly derived
> from Newton's
> laws) to calculate a numerical quantity you are on the solid ground of a
> mathematical model - a testable numerical equality.
>
> When you interpret these numerical results in terms of "particular energy
> losses, gains, transfers, transformations, etc  among particular objects",
> you are in the completely different realm of a conceptual model - a shaky
> ground of subjective taste based on metaphorical associations
> with everyday
> real and imagined human experience.
>
> You can do your students no greater service than to emphasize this
> distinction when you explain "How you know".