Andy, 1 Pa = 1 N/sq. meter, a very impractical unit. Therefore, the "bar" as the most commonly used pressure unit of today, not a SI unit, is only accepted as an exception to be near the previously used "atmosphere" = 1 kp/sq.cm. 1 hPa (hectoPascal) = 100 Pa (greek: hekaton = hundred). The heck with it. 1 bar = 100 000 Pa = 1.02 kp/sq.cm, so 1 mbar = 1.02 hPa. The lenght of a "1 meter pendulum" giving exactly one second is about 0.994 m, a bare coincidence. The meter was first defined as 1/40 000 of the earth's circumference and later on by the length of the platimum-iridium specimen in Paris. The factor of 9.81 is owed to the earth's a acceleration of a falling piece of mass measured to be g = 9.81 m/s squared, purely accidental.
Greetings Peter andy pugh schrieb: > There is a similar situation with the engine controllers I work on, > where there is a tendency to use heck Pascals (hPa) which are > coincidentally almost exactly the same as millibars. > I do think that this is purely a happy coincidence, as the Pascal > depends purely on the definitions of the kilogram and meter, with no > reference to atmospheric constants. > I think that the kg to Newton correspondence (9.81) might be less > accidental, being vaguely linked to the original definition of the > meter as the length of a "seconds pendulum" > > ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
