I used km/ks as a comparison with km/h, keeping the top unit the same, instead of 27800 km/s.
The problem with your explanation is that you say it "makes sense" to use hours only because "you know" hours. You could just as well say that it makes sense to use miles because you know how many miles it is. That is not a good argument for not converting to metric units. Most Americans would not be able to easily calculate their travel time from km/h, because they use miles, but does that mean that they should continue to use mph? The whole point of conversion (metrication) is getting people used to thinking metric. They should be able to wrap their minds around m/s just as you expect them to switch from miles to kilometers, if they get used to using kiloseconds, as well. I'm aware that the hour is accepted for use with SI, but it is still not a metric unit. It is not a multiple formed by adding a prefix to the base unit of time interval, nor is it a derived unit. And it is not just the common people who use these "accepted" units, i.e. minutes, hours and days. These units are used by scientists, as well, instead of kiloseconds, etc. It just seems ironic to me that we aren't considering kiloseconds along with the rest of the metric system. The day is based on a natural interval (although the SI day is defined as being exactly 86400 SI seconds) but hours and minutes have no basis in nature and we could probably get used to using kiloseconds, even though there are not a round number of them in a day. We could make clocks which count from 00.000 to 86.399 ks, for instance. Maybe our TV shows could be made longer or shorter to accomodate a round number of ks, maybe 2 or 4 ks instead of 30 or 60 min. John Hynes ----- Original Message ----- From: "Bill Potts" <[EMAIL PROTECTED]> To: "U.S. Metric Association" <[EMAIL PROTECTED]> Sent: Tuesday, December 07, 2004 1:39 AM Subject: [USMA:31597] RE: Some decimal time... jabs > Your km/ks (a deprecated form) and meters per second (m/s) are, of course, > the same thing. > > Minutes and hours, although not purely SI themselves, are accepted for use > with SI. > > For scientific purposes, of course, speed is indeed expressed in m/s. > However, as longer journeys (as opposed to trips to the store) may take > several hours, expressing speed in km/h makes sense. If you have 240 km to > go and the limit is 120 km/h, you know it's going to take 2 hours (assuming > no delays). If you have 255 km to go, you know it's going to take a little > over 2 hours (7.5 minutes over if you're good at mental arithmetic and want > to be really picky). > > If 120 km/h is expressed in m/s, it comes to about 35 m/s. If you were 240 > km from your destination and the limit was posted as 35 m/s, would you be > able to easily estimate your travel time? Would most people? > > Common sense is important to the successful implementation (and popular > acceptance) of SI. > > Bill Potts, CMS > Roseville, CA > http://metric1.org [SI Navigator] > > > >-----Original Message----- > >From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > >Behalf Of John Hynes > >Sent: Monday, December 06, 2004 22:19 > >To: U.S. Metric Association > >Subject: [USMA:31596] RE: Some decimal time... jabs > > > > > >So, why do metric road signs say, "Speed Limit 100 km/h"? Is this metric, > >or not? Why are not speeds expressed in seconds, or kiloseconds? The same > >speed could be written (approximately) as 28 km/ks. If we are going to > >promote the metric system, i.e. SI, and the hour is not part of SI, then > >shouldn't speed limits be defined in meters per second or some such? > > > >In fact, it seems that just about anywhere SI is used, whenever times are > >expressed, such as for radioisotope half-lives, instead of kiloseconds, > >megaseconds, gigaseconds, etc., minutes, hours, days, years, etc., > >are used. > > > >What's the difference between using hours and using miles or pounds? > > > >John Hynes > > > > --- Bill Hooper wrote: > >> The problem seems to be decimalization of the way we measure time of > >> day (in minutes and hours). Change the minutes and hours if you wish > >> (they are not part of SI anyway), but leave the second (and the metre) > >> alone. > > > >
