Date: Fri, 19 Sep 2003 09:48:15 -0400

Author: gnunes

Subject: Re: Newton's Third Law


For the price, a new one looks like a better deal. You could also
complain until the company offers to fix it under warranty.

As for the mercury, one of the local HS teachers gave me all of his
mercury thermometers. I understand that Indiana now prohibits mercury
in the schools. If that happens in your state, you'll have to get rid
of it anyway.

Mercury is pretty valuable stuff nonetheless. You might try to sell it.


On Thursday, September 18, 2003, at 08:43 PM, Bill Reitz wrote:

> A Chemistry teacher came to me today about a mercury barometer he had
> in the
> classroom at our high school. Students noted a couple of drops of Hg
> on the
> outside of the bottom of the apparatus. He said there also seemed to
> be a
> bubble in the mercury column. The barometer is only 2 years old and
> cost a
> whopping $400. He called the company that manufactured it. They said
> to mail
> it to them and they would reseal and refill it ( for $280). They also
> said
> that it had to be sent in a special box ( they'll provide one for $40).
> The Chemistry teacher didn't know whether to send it back to be
> refurbished
> for big bucks or just drop it in the hallway so that we could have a
> few
> days off. At nearby elementary school a small mercury spill was found
> on the
> floor in a science room. The school has been closed for a week. There
> is a
> rumor that a custodian collected the spill & poured it down the drain
> ("I
> didn't know it was mercury...") All the drains were sucked clean and
> some
> sealed off as a result.
> My question: what would you do with our troublesome barometer?
> Bill Reitz
From Fri Sep 19 07:05:18 2003
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Date: Fri, 19 Sep 2003 09:48:15 -0400
From: gnunes
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Subject: Re: Newton's Third Law
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Rick Tarara wrote:
> Let me say something that may be heretical. I'm not sure what
> _understanding_ Newton's Third Law means.....

This is an excellent point. My approach has been to emphasize
_interactions_ rather than forces. If you start from the idea of two
objects interacting, with the force as the observed effect of the
interaction, then it is natural to expect these forces to come in pairs
(or possibly pears). It is still a hard concept to teach effectively,
but this approach helped my students.

-Geoff Nunes
From Fri Sep 19 08:08:54 2003