Re: Introducing WORK

["Rick Tarara" <rtarara@saintmarys.edu>]

-----Original Message-----
From: Ludwik Kowalski <kowalskiL@Mail.Montclair.edu>


> Having a different name for a process, as opposed to names of
> physical quantities, is desirable, in my opinion. Perhaps mechanical
> processes will one day be described without using work but at this
> time we introduce work to students before we introduce energy.
> I can not use work-energy theorem before the concept of kinetic
> energy is defined as a quantity expressed in Joules. Well, I am now
> referring to Rick's message.

I, like Ludwik, will be starting Work and Energy today, but unlike past
years, I have already covered momentum and collisions.  To deal with Elastic
collisions, I needed to introduce KE, so I did so as a simple 'book-keeping'
tool.  We have not really discussed Energy per se, but rather recognized
that we can calculate this quantity that is named Kinetic Energy and that,
in certain types of collisions, this quantity is conserved and is therefore
useful in helping us predict the results of a given collision OR to measure
certain parameters of the collision (such as the mass of a target particle.)
This week we'll do a lab where they will measure (this is my 'liberal arts'
class) the mass of an airtrack cart by measuring the velocity before and
after a collision between a cart of known mass and the unknown.  Anyway, by
introducing the quantity of Kinetic Energy prior to dealing with the
concepts of Work and Energy, I hope to move very quickly from work to the
work-energy theorem.  We'll see if this 'works'.

Rick

P.S.  I always start this segment of the course by telling the class that
they have done no 'work' for the class up to this point.  This always stirs
up some consternation!  ;-)