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Re: misconception re ice melting under skates



Leigh,

Thanks for your answer. I dare to respond to your message in a changed order.

Leave out the "In correspondence to its heat
conductivity", but why lie? Hewitt obviously knows the truth and he
*oversimplifies*. I think that is clearly unjustifiable in this case,
and I can't imagine any reasonable defense of Hewitt's (reported)
statement. It can only be defended as a matter of taste, and it tastes
awful to me!

I understood what you mean saying that the locution "plastic wire
won't do it" is a lie. Your claim is definitely true in a civil court,
before a judge. In my view, it is not always applicable in a classroom. I
dare to remind you about great minds who made claims as "all objects fall
at the same rate", "period of swings is independent of the length of
pendulum," "a collision of steal balls is always perfectly elastic", or
(another class) "weight is gravitational force", "light is compound of
rays", "mass is energy", etc. Generations of physicists after them did
not have any problem to understand the boundaries of the validity of these
claims made by humans, together with the awareness of possible
misinterpretation when taken them verbatim. You say they were misleading.
Might be, in one educational event. But in any case there is no such thing
as a single instruction. It is impossible to make all reservations for all
cases, in each presentation. Learning is a long process, we approach the
scientific knowledge by converging (rising, if you want) steps of
education. On this way, it is legal to use different levels of exposure of
material depending on goals and the audience.

Saying that plastic string won't do it is a misconception
of the simplest kind. It is not a simplification; it is (simply) wrong.
Would it have exceded the bounds of reading level to say that the
plastic string would pass through the cube much more slowly because it
has a much lower capability for transferring heat than the metal wire?
(Sorry, Ludwik; that's the way I would do it in a course for
unsophisticated students.)

I wouldn't mind to learn from you in this mode. By the way, I do have a
rich experience with students of the advanced physics courses who did not
get fundamental conceptual knowledge in physics.

For me this discussion illustrates the everlasting contradiction
between the demands of phenomenological and rigorous presentations of
physics. Both extremes are simply not feasible. Each physics teacher
prepares a unique ratio of both approaches in each particular
circumstances.

I remain inflexible.

Then, in this domain, we belong to different cultures.
Peace and best wishes.
Igal.