On Wednesday 25 January 2006 04:44, John Hynes wrote:
> In the US, speeds are usually regulated in increments of 5 mph.  (I have
> seen one or two exceptions.)  1 m/s is about 2.237 mph, so here are some
> rounded conversions:
>
> MPH   m/s    km/h
>  5         2         8
> 10        4        16
> 15        7        24
> 20        9        32
> 25       11       40
> 30       13       48
> 35       16       56
> 40       18       64
> 45       20       72
> 50       22       80
> 55       25       89
> 60       27       97
> 65       29      105
> 70       31      113
> 75       34      121
>
> It is not hard to imagine that if road speeds were to be expressed in m/s,
> that a smaller number of 5 m/s increments would be used.
>
> m/s   MPH     km/h
>  5        11       18
> 10       22       36
> 15       34       54
> 20       45       72
> 25       56       90
> 30       67      108
> 35       78      126

To keep about the same increment as the 5 mph, it might be a good idea to use 
an increment of 9 km/h, thus making speeds that can be converted exactly to 
m/s (the unit to use when thinking about a car accident) without any trailing 
repeating decimals.

phma

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