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### Doubling Zero?

```Date: 02/13/2007 at 06:19:07
From: Claire
Subject: (no subject)

I have a student who asked, "What is twice as cold as zero?"

```

```
Date: 02/13/2007 at 09:29:46
From: Doctor Ian
Subject: Re:

Hi Claire,

It's not really a sensible concept, because temperature is a relative
measurement, not an absolute one (like length, or mass).

What you CAN sensibly ask is something like:

In the _____ scale, what temperature is twice as
far from zero degrees as _____ degrees?

For example, it makes sense to say that

In the Celsius scale, 48 degrees is twice as far
from 0 degrees as 24 degrees.

But that doesn't make it "twice as hot".  When asked this way, you can
say that

In the Celsius scale, 0 degrees is twice as far
from 0 degrees as 0 degrees.

But this doesn't mean that 0 is "twice as cold" as zero.

The real lesson here is that just because you can form a question that
is grammatical, that doesn't mean the question makes sense, or has an

Does this help?

- Doctor Ian, The Math Forum
http://mathforum.org/dr.math/

```

```
Date: 02/14/2007 at 00:36:26
From: Claire
Subject: Thank you ((no subject))

Thank you - that makes sense!!!
```
Associated Topics:
Elementary Temperature
Middle School Temperature

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