I am not convinced! One of the criteria needed in driving on the roads is the need to provide some form of relationship between speed and distance over time we that can relate to. If distance is measured in km, then speed needs to also use km, and km/h is as convenient a measure as any.
I once wrote to Road and Track (US auto magazine) providing a counter argument to technical editor Denis Simonaitis's (I think that is how his name is spelled) assertion that imperial measures have some handy 'yardsticks', such as 60 mph is equal to 1 mile per minute. My argument was that metric has even more (and better): 1. Urban journeys are generally measured in minutes. A good urban average is 60 km/h (equal to 1 km per minute), therefore a journey of say 15 km will take 15 minutes. 2. Long distance journeys are generally measured in hours. A good freeway average is 100 km/h, therefore a journey of 450 km will take 4.5 hours. 3. And a (perhaps slightly over the speed limit) rate of progress on the freeway of 120 km/h will mean that the kilometres are slipping by at the rate of 2 km per minute - useful in calculating the time to your next exit. I was quite gratified that Denis devoted a good section of his next article in putting my case forward. I cannot see though how the use of m/s would fit in with any of the above, as metres (except in short distances to intersections and the like) are not used in measuring travel distances on the roads, and seconds are not used to measure time taken. Regards John F-L ----- Original Message ----- From: Pat Naughtin To: U.S. Metric Association Sent: Wednesday, July 15, 2009 1:47 AM Subject: [USMA:45365] Speed in metres per second Dear All, I have just been reading this blog at http://globonsomeday.blogspot.com/2009/07/improving-metric-system.html where they say: Another metric unit commonly encountered in everyday usage is the unit of speed, kilometres per hour. The official SI base unit for time is seconds, and therefore a more appropriate measurement of speed is metres per second. For example, 100 km/h is equivalent to 27.78 m/s. I wonder if we will ever be ready to embrace the idea of using the SI unit, metres per second, for speed in everyday conversations. Let's take the example given above with sensible rounding. The speed limit on a highway might then become 25 metres per second. Other limits might go like this (using Australian examples): School zone 40 km/h 10 m/s Suburban street 60 km/h 15 m/s Main (4 lane) cross town road 70 km/h 20 m/s Highway 100 km/h 25 m/s Freeway 110 km/h 30 m/s It might be interesting to see this idea applied to speed limits in Asia, Europe, the UK and the USA. Cheers, Pat Naughtin Author of the forthcoming book, Metrication Leaders Guide. PO Box 305 Belmont 3216, Geelong, Australia Phone: 61 3 5241 2008 Metric system consultant, writer, and speaker, Pat Naughtin, has helped thousands of people and hundreds of companies upgrade to the modern metric system smoothly, quickly, and so economically that they now save thousands each year when buying, processing, or selling for their businesses. Pat provides services and resources for many different trades, crafts, and professions for commercial, industrial and government metrication leaders in Asia, Europe, and in the USA. Pat's clients include the Australian Government, Google, NASA, NIST, and the metric associations of Canada, the UK, and the USA. See http://www.metricationmatters.com for more metrication information, contact Pat at pat.naugh...@metricationmatters.com or to get the free 'Metrication matters' newsletter go to: http://www.metricationmatters.com/newsletter to subscribe.
