I think /s would be more understood by most people and s-1 would look strange. Also, shouldn't the form be s^-1 with the addition of the ^ symbol to indicate an exponent?
Jerry ________________________________ From: James R. Frysinger <[email protected]> To: U.S. Metric Association <[email protected]> Cc: U.S. Metric Association <[email protected]> Sent: Sunday, March 22, 2009 9:41:44 PM Subject: [USMA:44069] Re: SI 10 question If you prefer, Stan, please read my 8600/s as 8600 s-1. It seems both of us understand each form. I of course accept the latter as being quite valid. Jim Stan Jakuba wrote: > > You must be joking, Jim. Who would ever write 8600/s? In SI or in anything > else! Of course, you can SAY whatever you want, but the subject here is the > WRITTEN language of SI symbols. > > It has been the common practice in technical literature for decades > (including in the US, UK, and similar) to write 8600 s^-1 or 8600 min^-1, to > use your number. > > If you had read the three paragraphs carefully (you had seen them many times > before) you'd see that, contrary to what you say, those units make confusion > impossible. Yes, to understand them, a bit of education helps but such > education is provided at the high-school level. But perhaps only in the > metric countries. > Stan Jakuba > > > ----- Original Message ----- From: "James R. Frysinger" > <[email protected]> > To: "U.S. Metric Association" <[email protected]> > Sent: 09 Mar 22, Sunday 14:47 > Subject: [USMA:44061] Re: SI 10 question > > >> >> You may wish to consult Section 8.1 of NIST SP 811. One has to be >> careful with using 1/s (or s-1) for rotational rates. There is potential >> confusion whether one means shaft rotations per second or angular >> velocities of radians per second. 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. >> >> Jim >> >> Stan Jakuba wrote: >>> >>> FREQUENCY >>> >>> >>> >>> There are three kinds of frequencies, and correspondingly three different >>> units: >>> >>> >>> >>> -- Angular Frequency, commonly called angular velocity. Its unit is rad/s. >>> >>> >>> >>> -- Cycle Frequency. It is defined as the number of periodic events (cycles) >>> per second. This unit was given the name hertz (in honor of the German >>> scientist), symbol Hz. >>> >>> >>> >>> -- Rotational Frequency, commonly called speed of rotation or simply speed. >>> Its unit is s-1 optionally written also as 1/s. >>> >>> >>> >>> Note: The units of the cycle frequency and rotational frequency are >>> sometimes, and incorrectly, written as c/s or cps, and r/s or rps, >>> respectively. These symbols could be misunderstood in non-English speaking >>> countries. Furthermore, cycles and revolutions are not units; if used, >>> these words should be spelled out or clearly abbreviated such as rev./s, >>> rev./min., etc. >>> >>> Stan Jakuba >>> >>> >>> >>> ----- Original Message ----- From: "James R. Frysinger" >>> <[email protected]> >>> To: <[email protected]> >>> Sent: 09 Mar 14, Saturday 22:25 >>> Subject: Re: [SI] SI 10 question >>> >>> >>>> Paul, >>>> >>>> Rotational speeds are usually given as revolutions per second or >>>> revolutions per minute. To that point, one would want to list both r/s and >>>> r/min. Some folks use Hz instead of r/s, especially for shaft rotational >>>> rates since that is a periodic function (angular position as a function of >>>> time). >>>> >>>> In my physics classes I required my students to use r/min rather than rpm. >>>> >>>> Jim >>>> >>>> Paul Trusten wrote: >>>>> Bruce, this is revolutionary! (grin). I never thought of symbolizing >>>>> that, and it should be symbolized, since we avoid KPH in favor of the >>>>> correct km/h. >>>>> >>>>> Would it be more elegant, to use the base unit of time, and make the >>>>> quantity revolutions per second, proposed symbol r/s? That would make, >>>>> let's say, 5000 r/min change to about 80 r/s. I think perhaps not, since >>>>> r/min is an established unit. >>>>> >>>>> Paul >>>>> >>>>> ----- Original Message ----- From: "Bruce Barrow" <[email protected]> >>>>> To: <[email protected]> >>>>> Sent: 14 March, 2009 20:19 >>>>> Subject: Re: [SI] SI 10 question >>>>> >>>>> >>>>>> Mr. Bowman, >>>>>> >>>>>> You are coming up with some very good questions! Our IEEE Std on Unit >>>>>> Symbols, Std 260.1-2004, lists r/min as the appropriate unit symbol, and >>>>>> includes as a note, "Although use of rpm as an abbreviation is common, it >>>>>> should not be used as a symbol." I'm not sure ordinary mortals, as >>>>>> opposed >>>>>> to members of selected standards committees, understand the difference. >>>>>> >>>>>> I am proposing that our revised SI10 include only "r/min". >>>>>> >>>>>> Bruce >>>>>> >>>>>> ----- Original Message ----- From: "Lyle Bowman" <[email protected]> >>>>>> To: "Bruce Barrow" <[email protected]> >>>>>> Sent: Thursday, March 12, 2009 1:17 PM >>>>>> Subject: FW: SI 10 question >>>>>> >>>>>> >>>>>>> Mr. Barrow, >>>>>>> >>>>>>> Jim may have forwarded my question re 'rpm' (shown below) to you >>>>>>> already. >>>>>>> Had I known you were the person more directly responsible for the SI 10 >>>>>>> standard, I would have sent the request directly to you. >>>>>>> >>>>>>> Lyle Bowman. >>>>>>> >>>>>>> ------ Forwarded Message >>>>>>> From: Lyle Bowman <[email protected]> >>>>>>> Date: Tue, 10 Mar 2009 15:12:50 -0700 >>>>>>> To: "James R. Frysinger" <[email protected]> >>>>>>> Conversation: SI 10 question >>>>>>> Subject: FW: SI 10 question >>>>>>> >>>>>>> Jim, >>>>>>> >>>>>>> Thanks for the prompt response to my question. >>>>>>> >>>>>>> Perhaps, you can help me with another question also. In Table A.1 of the >>>>>>> SI >>>>>>> 10 standard (Page 36), the 'to convert from' column lists 'revolutions >>>>>>> per >>>>>>> minute (rpm)'. The previous E 380 standard listed both rpm and r/min, >>>>>>> and >>>>>>> I >>>>>>> note that the BIPM SI Brochure also lists both of these. The ASTM Form >>>>>>> and >>>>>>> Style for ASTM Standards document lists just r/min. Since the SI 10 has >>>>>>> been >>>>>>> my 'bible' for revising the some 35 ASTM standards I'm responsible for, >>>>>>> I've >>>>>>> used 'rpm' in those revisions. >>>>>>> >>>>>>> My question is why does the SI 10 standard list only 'rpm'? >>>>>>> >>>>>>> I've conjectured that 'rpm' was preferred because it definitely would >>>>>>> not >>>>>>> be >>>>>>> mistaken for a SI unit, but 'r/min' might possibly be. >>>>>>> >>>>>>> Regards, >>>>>>> >>>>>>> Lyle. >>>>>>> >>>>>>> ------ Forwarded Message >>>>>>> From: "James R. Frysinger" <[email protected]> >>>>>>> Date: Tue, 10 Mar 2009 16:02:43 -0500 >>>>>>> To: Lyle Bowman <[email protected]> >>>>>>> Cc: <[email protected]>, <[email protected]>, <[email protected]>, >>>>>>> <[email protected]>, <[email protected]>, <[email protected]>, >>>>>>> <[email protected]> >>>>>>> Subject: Re: SI 10 question >>>>>>> >>>>>>> Dear Mr. Bowman, >>>>>>> >>>>>>> I am the chair of a committee, some members of which represent the IEEE >>>>>>> portion of the IEEE/ASTM Joint Committee for Maintaining SI 10. Your >>>>>>> message has been forwarded to me for a reply. >>>>>>> >>>>>>> Standard practice in the U.S. is to use a space instead of a hyphen when >>>>>>> unit symbols are used, whether the expression is in noun ("a width of 35 >>>>>>> mm") or adjectival form ("35 mm film"). That would comply with the >>>>>>> normative statements of IEEE/ASTM SI 10 as well as NIST SP 811. Further, >>>>>>> and importantly, it complies with Section 5.3.3 of the SI Brochure (8th >>>>>>> ed.) >>>>>>> >>>>>>> Your suggestion to make an explicit statement in SI 10 regarding >>>>>>> application of this practice to the adjectival form is noted and will be >>>>>>> considered for the revision (update) now in progress. Thank you for that >>>>>>> thought! >>>>>>> >>>>>>> You may have noticed that SP 811 says the hyphen "is acceptable" (but >>>>>>> not required) in adjectival forms when the unit name is spelled out >>>>>>> ("35-millimeter film"). Personally, I prefer using a space there as >>>>>>> well; the movement in language is generally toward economy of >>>>>>> punctuation, except as needed to avoid ambiguity. >>>>>>> >>>>>>> Thank you very much for your interest in SI 10. Most certainly, we are >>>>>>> pleased to hear that you are working towards improved metrication of >>>>>>> ASTM standards. If you have any other questions, please do not hesitate >>>>>>> to write or call. >>>>>>> >>>>>>> regards, >>>>>>> James R. Frysinger (Jim) >>>>>>> Chair, Standards Coordinating Committee 14 >>>>>>> IEEE Standards Association >>>>>>> >>>>>>> [email protected] wrote: >>>>>>>> >>>>>>>> Jim, >>>>>>>> >>>>>>>> Please see the communication (below), regarding SI 10. >>>>>>>> >>>>>>>> Thanks, >>>>>>>> **************************************************************** >>>>>>>> David L. Ringle >>>>>>>> Manager - IEEE-SA Governance, Policy & Procedures >>>>>>>> IEEE Standards Activities Department >>>>>>>> 445 Hoes Lane >>>>>>>> Piscataway, NJ 08854-4141 USA >>>>>>>> TEL: +1 732 562 3806 >>>>>>>> FAX: +1 732 875 0524 >>>>>>>> [email protected] >>>>>>>> **************************************************************** >>>>>>>> >>>>>>>> March 4, 2009 >>>>>>>> >>>>>>>> I'm an ASTM member and have been given the task of revising the >>>>>>>> measurement units in many ASTM standards to SI units. >>>>>>>> >>>>>>>> The IEEE/ASTM SI 10-2002 standard has been my primary reference in >>>>>>>> doing >>>>>>>> this task. >>>>>>>> >>>>>>>> There's one question that I haven't been able to resolve, and that is >>>>>>>> whether to place a hyphen between a number and an SI unit when the >>>>>>>> combination is used in an adjectival sense. My SI 10 reference (Section >>>>>>>> 3.5.1, item d)) says to leave a space between a 'numerical value and a >>>>>>>> unit symbol', and does not comment on the possible adjectival usage. >>>>>>>> >>>>>>>> An earlier ASTM E 380 SI Standard says to hyphenate when the >>>>>>>> combination >>>>>>>> is used in an adjectival sense, and the current NIST Special >>>>>>>> Publication >>>>>>>> 811 (SP 811) says specifically not to hyphenate in that situation. >>>>>>>> >>>>>>>> Assuming that it's also the intention of the IEEE/ASTM 10-2002 standard >>>>>>>> to not hyphenate when a combination of a numerical value and a unit >>>>>>>> symbol is used in an adjectival sense, I'd recommend that a specific >>>>>>>> statement to that effect be included in the standard. >>>>>>>> >>>>>>>> I'd appreciate being informed if my above assumption is incorrect. >>>>>>>> >>>>>>>> Sincerely, >>>>>>>> Lyle Bowman >>>>>>>> 728 Montecillo Road >>>>>>>> San Rafael, CA 96904-3136 >>>>>>>> >>>>>>>> Phone: 415-479-3004 >>>>>>>> >>>>>>>> Email: [email protected] >>>>>>> >>>>>>> -- James R. Frysinger >>>>>>> 632 Stony Point Mountain Road >>>>>>> Doyle, TN 38559-3030 >>>>>>> >>>>>>> (C) 931.212.0267 >>>>>>> (H) 931.657.3107 >>>>>>> (F) 931.657.3108 >>>>>>> >>>>>>> >>>>>>> ------ End of Forwarded Message >>>>>>> >>>>>>> ------ End of Forwarded Message >>>>>>> >>>>>>> >>>>>> >>>>>> >>>>>> >>>>> >>>>> >>>>> >>>> >>>> -- James R. Frysinger >>>> 632 Stony Point Mountain Road >>>> Doyle, TN 38559-3030 >>>> >>>> (C) 931.212.0267 >>>> (H) 931.657.3107 >>>> (F) 931.657.3108 >>> >>> >>> >>> >> >> -- James R. Frysinger >> 632 Stony Point Mountain Road >> Doyle, TN 38559-3030 >> >> (C) 931.212.0267 >> (H) 931.657.3107 >> (F) 931.657.3108 >> > > > > -- James R. Frysinger 632 Stony Point Mountain Road Doyle, TN 38559-3030 (C) 931.212.0267 (H) 931.657.3107 (F) 931.657.3108
