[time-nuts] SI Unit Problems

Arnold Tibus arnold.tibus at gmx.de
Tue Apr 5 17:26:31 UTC 2011


I don't understand what is wrong with 'Hz'.
As Time in seconds is a SI unit, Frequency is the reciprocal value of
time, f=1/T, Frequency is not a SI base unit but a SI coherent derived
unit (in the list with special names and symbols as force, pressure,
charge, power, resistance etc.). [11th CGPM, Resolution 12]

So Frequency is defined as the measure of the number of occurrences of a
repeating event per unit time. To calculate the frequency, the number of
occurrences of the event within a fixed time interval are counted, and
then it's divided by the length of the time interval.

NIST wording: "The rotational frequency n of a rotating body is defined
to be the number of revolutions it makes in a time interval divided by
that time interval [4: ISO 80000-3]. The SI unit of this quantity is
thus the reciprocal second (s-1)".

But perhaps I misunderstand your position, could you give an explanation?

Arnold

Am 05.04.2011 17:54, schrieb Brooke Clarke:
> Hi Jim:
> 
> But what you show violates the SI rules, even though it's the correct
> calculation.
> 
> Have Fun,
> 
> Brooke Clarke
> http://www.PRC68.com
> 
> 
> Jim Lux wrote:
>> On 4/5/11 8:25 AM, Brooke Clarke wrote:
>>> Hi:
>>>
>>> Just reading at:
>>> http://futureboy.us/frinkdata/units.txt
>>>
>>> First about the candela and all it's problems, then what's a Time Nut
>>> issue  "Hz ".
>>>
>>> // This means that, if you follow the rules of the SI,
>>> // 1 Hz = 1/s = 1 radian/s which is simply inconsistent and violates
>>> basic
>>> // ideas of sinusoidal motion, and is simply a stupid definition.
>>>
>> actually 1/s (= Hz) = 2*pi rad/sec
>>
>> BTW, if anyone is confused, I have a handy direct reading graph
>> published by HP a few decades ago to assist engineers in converting
>> from cycles per second to Hertz.  I'll see if I can scan it and attach
>> it later.  I know I really should have mentioned this last Friday.
>>




More information about the Time-nuts_lists.febo.com mailing list