Abandoning a unit because it is not on the genarally accepted list of metric units may not be wise. You are mucking about with some fundamental concepts of math and trigonometry. What would you propose as a substitute for angular measurement instead of radians?
The "Unit Circle" has an angular measurment of 2*Pi radians, where Pi is a real number (only approximated as 3.14159 . . .). This is a starting point for nearly everything we do with trigonomitry. When an object is undergoing angular diplacement, we say it is "rotating". once the angular displacement equals 360 degrees or 2Pi radians, it has completed one revolution. The 1st integral of displacement gives us displacement per unit time, or angular velocity, also referred to and rotational speed (though this less accurate term ignores the vector quantity of direction). The 2nd tntegral of displacement (or 1st integral of velocity) gives us the rate of change of the velocity, or "acceleration". This little walk through the calculus helps us understand and deal with the physical realities of circular things. It is not Metric. It is not English, or Imperial. It is Trigonometry. To redifine the Unit Circle to be equal to 100 "Metric Degrees", for example would then force all of the universally understood identities of trigonometry to be revised for no good reason. The circle was defined as 360 degrees for good reasons, along with the length of an earth day. These concepts were not defined based on silly and arbitrary ideas like the size of the King's foot, or the length of his arm, or the width of his thumb. I think this forum needs to try and focus more on how to promote the use of the metric system within the USA, rather than debating some of the "nit-picky" minutia that has been wasting a great deal of bandwidth, or looking for other things to metricate that maybe don't need it. What next, a metric Farad? Aaron Harper On Mon, Mar 23, 2009 at 3:41 PM, Bill Hooper <[email protected]>wrote: > > On Mar 22 , at 2:47 PM, James R. Frysinger wrote: > > So if I say, "The motor is running at > 8600/s" what do I mean? Better to say, "The motor is running at a shaft > rotation rate of 8600/s" or "The motor is running at an angular velocity > of 8600 rad/s", whichever is the case. Of course those differ by a > factor of 2 pi. > > > I agree with this (above) and would further argue that, if we indeed do > insist on naming the measured rate by proper names like "rotation rate", > "angular velocity" etc. then it should be possible to see that rotations are > not units and the, correspondingly, neither are radians. > > (Since degrees per second are also used for angular velocity, one would > need different names for these two things. I'd suggest "degree velocity" and > "radian velocity".) > > Abandoning the practice (built firmly into SI) of treating the radian as a > unit would, in my opinion, be progress. > > Regards, > Bill Hooper > Fernandina Beach, Florida, USA > > PS And I remembered to change the subject on this as I go off on a tangent. > > ========================== > Make It Simple; Make It Metric! > ========================== > > > >
