Re: physics/pedagogy of coffee-mixing

[brian whatcott <inet@INTELLISYS.NET>]

At 12:47 6/25/00 -0400, you wrote:
> ...
> Model each cup as an urn with 1000 balls, black for the coffee and
> red for the tea. Suppose one spoonful means 10 balls ...

> After the first transfer we have 990 black balls in one cup and a
> mixture of 1010 balls in another. What happens after the second
> transfer? It is unlikely that the second spoon will contain more
> than one or two black balls.

(numbers for 2 black balls returned)
First Transfer
--------------
Cup 1 990 black       Cup 2 1000 red 10 black

Second Transfer
---------------
C1: 990 black + 8 red + 2 black = 992B+8R      C2: 992 red + 8
black=992R+8B

> ... On that basis my answer is that
> there is more coffee in the tea than tea in the coffee.

Gotcha!.....


> To which category does my answer belong? Please summarize
> these "several ways", if you can.

There's the right way, and there's the wrong ways...

> > So the questions for today are
> >   *) Why do people have a hard time with this riddle?

It's a conceptual sleight of hand of the same kind that magicians use:
a misdirection....physicists set to reviewing spoon bending type
 experiments are notoriously weak at spotting misdirection.

 It's obvious that after one transfer, the mix ratios of two
containers are different, after all!



brian whatcott <inet@intellisys.net>
Altus OK