Chronology Current Month Current Thread Current Date [Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

# Re: [Phys-l] frequency: a modest proposal

• From: John Denker <jsd@av8n.com>
• Date: Wed, 27 Jan 2010 05:48:44 -0700

On 01/27/2010 01:33 AM, James McLean wrote in part:

... why not define the unit 'cycle' = 2pi radians, and then make
1 Hz = 1 cycle/s = 2pi radians/s = 2pi/s ?

That makes sense ... and is indeed the only definition
I have ever used, or ever heard of, until now.

I've always been mildly disturbed by the definition of the unit hertz as
equivalent to 1/second. (Such as can be found, for example, at
<http://physics.nist.gov/cuu/Units/units.html> and
<http://physics.nist.gov/cuu/Units/SIdiagram.html>.

I'm surprised. I've never noticed that before. It
looks like a bug to me.

Can anyone see any problems with this [radian] option, other than the near

It's not a problem. It's not even a change. Radians
and radians per second (not cycles per second) are
electrical engineering, and in every physics book I
can think of.

I cannot imagine any argument in favor of cycles/sec
as equivalent to 1/sec. I have to assume that those
two NIST pages are just mistakes.

Suggestion: Send a short note to the NIST guys and
suggest they repair the web page to show Hz as
2π radians per second? Or call 'em on the phone.

I would hope a very short note would suffice. That
is, I hope it is not necessary to argue the point.
It should suffice to say that 2π radians per second
is consistent with the other units on the page, and
s^-1 is not consistent. I cannot imagine there would
be any sort of counterargument.