Re: RADIANS

[Rick Tarara <rtarara@SAINTMARYS.EDU>]

We also measure temperature in 'degrees' (Celsius, Fahrenheit, etc.) and
there are no dimensions there--although a standard thermometer does convert
a 'length' to a temperature though calibration.  There is no intrinsic
physics involved in the size of a degree (either temperature or angular).
These are somewhat arbitrary choices that have been made.  There are plenty
of other physical quantities without units--coefficients of friction,
indices of refraction, efficiencies, etc.

How is an angle measured?  _How are the instruments calibrated?_  Why does a
measured quantity need dimensions?

Rick

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Richard W. Tarara
Associate Professor of Physics
Saint Mary's College
Notre Dame, IN 46556
rtarara@saintmarys.edu

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----- Original Message -----
From: "Doug Craigen" <dcc@ESCAPE.CA>
To: <PHYS-L@lists.nau.edu>
Sent: Wednesday, November 29, 2000 10:21 AM
Subject: Re: RADIANS


> Tim O'Donnell wrote:
> > > Radians ARE units, just as degrees are.  They're dimensionless.
> > > Wolfgang
> >
> > Since I can measure both, how can they have no dimensions?
> > Tim O'Donnell
>
> You can measure lots of things that have no dimensions.  For example the
> aspect ratio of a rectangle - height/width - has no dimensions.
> Similarly for an angular measurement (arc length/radius)
>
>
> \_/^\_/^\_/^\_/^\_/^\_/^\_/^\_/^\_/^\_/^\_/^\_/^\_/^\
>
> Doug Craigen
>           http://www.dctech.com/physics/about_dc.html