Re: Stop using calories?

[herbgottlieb@juno.com]

James Mclean writes:

> > Herb says that  the trouble with using the calorie 
> > (or the bigger Calorie) as a unit, not
> > only adds unnecessary terms  for the beginning physics students
> > to learn, but it tends to reinforce the discredited concept that heat 
> > is an invisible substance (caloric) that can be added or removed 
> > from matter.
>
> How does it do that?  I doubt many intro students will have heard of
> 'caloric' so that they can make the word association.  


You are correct in saying that most students have never heard of the
caloric theory of heat. However almost all of them come to us with 
the misconception that heat is an invisible substance of some 
kind that they can feel but not see. When it is added to an object,
the object becomes hot.  When it is removed from something 
the object becomes cold.  

Haven't you ever heard of these misconceptions:

"You can take the heat out of a fever by adding cold compresses
to the forehead".  

"You can send heat upstairs by turning up the thermostat"

"In the winter, heat escapes through cracks and poorly 
insulated walls of your house."

"When a cold liquid is mixed with a warm liquid, the heat that
is gained by the cold liquid  is equal to the heat that is 
lost by the hot liquid until both are the same temperature."

Whether you call it caloric or or even "heat energy", lets get 
students away from the concept that heat is an invisible substance 
that.... ...... ...... etc. etc .....

Herfb Gottlieb from New York City
(Where our discussions about heat sometimes become overly heated)