### It Doesn't Take a Physicist to Correct a Physics Mistake

Comparing Temperatures

An article claimed — in its headline — that a ~5ºC (~10ºF) increase in temperature was an increase of 18.7 percent, by calculating using the relative temperature scale. Which is wrong, of course; e.g. 2ºC does not represent twice as much thermal energy as 1ºC. The site has since made a correction.

If you really want to do a percentage based comparison, you need to convert to an absolute temperature scale like Kelvin, which shows you that it’s actually a 1.8 percent increase in temperature (306.75 / 301.45). This is middle school science.

Sadly, I don’t think that this is generally taught in middle school. Or possibly even high school, except to a few students.

1. Schrödinger's hat on March 22nd, 2012

I’m pretty certain it’s taught to most students, especially highschool students that take a physics or chemistry course. Just forgotten immediately afterwards.

2. Drew on March 22nd, 2012

One could argue in this case that it’s the temperature over ambient that matters, since the phone is being cooled by the ambient air. In that case the iPad fares much worse than the claimed 18%.

3. Drew on March 22nd, 2012

D’oh! I called it a phone, didn’t I?

4. swansont on March 22nd, 2012

@Schrödinger’s hat — I was obliquely referring to the (many?) students that don’t take chemistry/physics.

@Drew — That’s true if you are analyzing energy and assume Newton’s law of cooling applies. If only the article had done that.