[time-nuts] 15 ns vs. 15 nS

Rob Kimberley rk at timing-consultants.com
Tue May 22 09:15:11 EDT 2007


Happy memories...

I remember being switched half way through my "A" Level Physics course from
cgs to MKS in 1968. 

Legal here in UK to show weights & measures in shops in both metric and
imperial systems. Fuel at petrol (gas) stations sold in litres, and distance
on roads still shown in miles (!!). Never did understand how the US gallon
was smaller than the Imperial one though...

Rob


-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of John Day
Sent: 22 May 2007 14:03
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] 15 ns vs. 15 nS

At 08:26 AM 5/22/2007, you wrote:
>I was basing my observation on the three fundamental units - M, K, & S, 
>as taught in the 60's. Just goes to show how things have changed...

You mean the old MKSA system? I was taught that in high school too, after we
abandoned the cgs system. But I was in Australia at the time. Metric
conversion started there in 1970 (I was in college by then), SI was
introduced to primary schools in 1972 and to high schools in 1973. For all
practical purposes, conversion to SI was complete by 1976.

So having started out with the centimetre, gramme, second system, moving to
the so-called 'rationalised' metre, kilogramme, second, Ampere system the
move to SI at university seemed trivial. The really difficult thing has been
to move to a partially metricated country in my 50's. Trying to delve back
into the recesses of my teenage years to once again work in pounds at the
food store has not been fun! Here in Canada it seems that we are legally
required to show prices in the store in both, or at least it is customary to
do so, but ask for something in metric quantity in many smaller stores and
it suddenly seems I have grown an extra head or two overnight. At least my
butcher now has a scale that will work in metric units!

John

PS: Don't get me started on trying to deal with US Customary measure when
living there in the 70's! Little did I realise that a gallon was not really
a gallon after all.

J


>Rob
>
>-----Original Message-----
>From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
>Behalf Of John Day
>Sent: 22 May 2007 12:43
>To: Discussion of precise time and frequency measurement
>Subject: Re: [time-nuts] 15 ns vs. 15 nS
>
>At 04:05 AM 5/22/2007, Rob Kimberley wrote:
> >As Seconds are a fundamental unit of the SI system, shouldn't the "S"
> >be upper case?
>
>Of seven SI 'base units' only two - K for thermodynamic temperature and A
>for electrical current are capitalised. On the basis of your suggestion we
>would need to campaign for a change in 5 units, not just one.
>
>John
>
>
> >Over to you fellow "nuts".
> >
> >Rob Kimberley
> >
> >-----Original Message-----
> >From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> >Behalf Of James Maynard
> >Sent: 22 May 2007 08:26
> >To: Discussion of precise time and frequency measurement
> >Subject: [time-nuts] 15 ns vs. 15 nS
> >
> >Didier Juges wrote:
> > > Sorry, it's not 15nS rms, it's 15nS at 1 sigma.
> > >
> > > Didier KO4BB
> > >
> > >
> >A long s we are being pedantic:
> >15 ns = 15 nanoseconds, but 15 nS = 15 nanosiemens.
> >
> >I am sure in the time-nuts list, we are concerned with nanoseconds, not
> >nanosiemens!
> >
> >
> >
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