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- From: gisle@ifi.uio.no (Gisle Hannemyr)
- Subject: Re: PV equation
- In-Reply-To: hardman@throb.mcws.fidonet.org's message of Thu, 12 Nov 92 01:32:15 PST
- Message-ID: <GISLE.92Nov15201718@gyda.ifi.uio.no>
- Sender: gisle@ifi.uio.no (Gisle Hannemyr)
- Organization: gisle@ifi.uio.no
- References: <GISLE.92Nov9222817@gyda.ifi.uio.no> <goD5TB2w165w@throb.mcws.fidonet.org>
- Date: Sun, 15 Nov 1992 19:17:18 GMT
- Lines: 171
- Originator: gisle@gyda.ifi.uio.no
-
- In article <goD5TB2w165w@throb.mcws.fidonet.org> hardman@throb.mcws.fidonet.org (Bill Hardman) writes:
-
- > gisle@ifi.uio.no (Gisle Hannemyr) writes:
-
- >> [[ The story so far: ph36@unixg.ubc.ca (Richard Nistuk) has come across
- >> a really weird equatuion in "Dianetics", and want somebody to explain
- >> it to him. The equation is:
- >>
- >> PV=I*D^x
- >>
- >> and we later learn that:
- >> PV = potential value of an individual or group
- >> I = intelligence (presumably IQ)
- >> D = the "Dynamic". This is a number between 1 and 4
- >> indicating where the individual are within 4 "dynamics".
- >> x = the magnitude on which the person is surviving on the
- >> dynamic, it is a number between 1 and 10
- >>
- >> Mr. Nistuk's basic question is "How do you apply the equation?",
- >> to which Mr. Hardman gives the snappy answer "Insert the known
- >> factors and use standard algebra". This doesn't seem to satisfy
- >> Mr. Niestuk, who keeps bringing up a strange thing called "units".
- >> Now -- let's return to the discussion...]]
-
-
- >> Bill:
- >>> To keep it simple for you, try using units of 1 to 10 [[for x?]].
- >>> The unit [[of the Dynamic]] is between 1 and 4.
-
- >> Eh, Bill, I think you've missed something really basic somewhere
- >> along the line. The word "unit", you see, is short for "unit
- >> of measurement", and is usually expressed in terms such as
- >> "seconds","kilos" "meters", "volts" or whatever. Numbers that
- >> doesn't have units, such as "1", "4" and "10" is referred to as
- >> "unitless".
- >>
- >> Units play a fairly significant part in standard algebra, where the
- >> SI (Systeme International d'Unites) devised to keep the units used
- >> in equations consistent.
- >>
- >> For example, the equation for speed is
- >>
- >> s = At
- >> where
- >> meaning unit
- >> ---------------------------------------
- >> s = speed 1 meter/second
- >> A = accelaration 1 meter * second^-2
- >> t = time 1 second
- >>
- >> now if we want to compute the speed of an object beeing
- >> accelarated by earth's gravity (9.8 ms^-2) in vacuum
- >> in 10 seconds we get:
- >>
- >> s = 9.8 ms^-2 * 10 s = 98 ms^-1 = 98 meter/second
- >>
- >> Please note that the algebra not only involved the quantities,
- >> but also the units, and that the unit of the answer became
- >> meter/second (meters per. second), which is a unit of measurement
- >> for speed.
-
- Bill:
- > Please note that you assigned the unit. You assigned meters, and
- > seconds as the unit measures. If you would have observed that in
- > the beginning, you wouldn't need long winded explanations of the
- > obvious.
-
- No, Bill, I didn't assign the units. When I learnt about this equation
- in high school, the text book that told me how to apply the equation
- also told me which units to use.
-
- In his very first posting, Richard Nistuk pointed out that the basic
- problems with the equation as it is expressed by L. Ron Hubbard, is
- that in his textbook, Hubbard doesn't tell you what units to use, or
- how to measure the values. The implication is of course that Mr.
- Hubbards claims about his theories being "science" must be taken with
- a pinch of salt if not even simple questions like these can be
- answered satisfactorily.
-
- Sometimes selecting appropriate units is trivial. Sometimes it isn't.
- For example -- if you do physics calculations involving temperature
- using degrees Celcius or Farhenheit as your unit of measurement, you
- may get some strange results. Using degrees Kelvin usually works much
- better. I would say that finding appropriate units for the PV
- equation is a non-trivial matter.
-
-
- > You could also substitute like units of measure and the
- > equation would still work, wouldn't it?
-
- Yes -- there are a number of alternative systems that all work. Some
- physics textbooks uses imperial units and will tell you how to apply
- this speed equation using inches instead of meters. With imperial
- units, the numbers become different, but the equations still work.
-
- Now let's try it out:
- Let's to some for speed calculations for the speed of an object
- accelarated in vacuum for 10 seconds on two planets with
- different gravities:
-
- Planet A Planet B
- metric imperial metric imperial
- Gravity: 9.8 ms-^2 385.8 is^-2 4.9 ms-^2 192.9 is-^2
- Time: 10 s 10 s 10 s 10 s
- Speed 98 m/s 3858 i/s 49 m/s 1929 i/s
-
- Let's compute the relative speed between the object accelarated
- at planet A and B for both our metric and our imperal measurements.
-
- Metric: 98 ms^-1 / 49 ms^-1 = 2
- Imperial: 3858 ms^-1 / 1929 ms^-1 = 2
-
- Note that it didn't matter which units we used -- in both cases we get
- the same results -- that objects would fall twice as fast on planet A
- than on B. Because computing relative values cancels the units, this
- is what you should expect. The realtive values are unitless, and
- therefore we should get the _same_ answer no matter what system was
- used for the measurement and the original computation (that is -- if
- the unit system and the theory behind equation make sense in the first
- place).
-
- Now, let's return to the PV equation:
-
- PV=I*D^x
-
- and compute the potential value of two persons in unit system X (since
- we don't know what they are, I'll leave out their symbols).
-
- Person A Person B
- I: 70 156
- D: 3 3
- x: 8 6
- PV: 459270 113724
-
- Let's do it again, using another range of values for x. (i.e. using a
- different unit measurement for x), this new unit happens to be exactly
- a tenth of the previous one, so we get (in unit system Y):
-
- Person A Person B
- I: 70 156
- D: 3 3
- x: 0.8 0.6
- PV: 168.6 301.6
-
- Now let's compute the relative PV of these two persons:
-
- Unit system X: 459270 / 113724 = 4.04
- Unit system Y: 168.6 / 301.6 = 0.56
-
- Isn't this strange? In one system, person A has a PV more than 4
- times that of person B. If I use another system, his PV computes to
- 56% of that of B? Which is correct? And why do this equation exhibit
- the strange feature that we get different results depending upon the
- range used for values of x?
-
- As always, Bill, I am looking forward to your explanation.
-
-
- PS: I apologize for ascribing the term "out-gradient" to you.
- As others has pointed out -- it was Jonathon who used that
- expression.
-
- --
- Meta-disclaimer: A society that needs disclaimers has too many lawyers.
-
- - gisle hannemyr (Norsk Regnesentral)
- OSI: C=no;PRMD=uninett;O=nr;S=Hannemyr;G=Gisle (X.400 SA format)
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