- View SourceI was thinking you could use the gauge mark a lot of rules have at 785. That might be too far off, though.

Sent from my iPad

On 2012-05-09, at 5:00 PM, Paul Hirose <cfuhb-acdgw@...> wrote:

> Recent news stories about obesity in America got me thinking about how a

> slide rule might be used to calculate BMI (body mass index). It's a

> function of a person's mass and height. Typically, a value over 25 is

> considered undesirable, and over 30 definitely obese. In SI units the

> formula is easy: m / h^2, where m is kilograms and h is meters.

>

> In pounds and inches, the formula is m / h^2 / 700. (Actually, 703 is a

> more accurate constant, but the difference is trivial.)

>

> As usual, there's more than one way to calculate that on a slide rule,

> and I came up with some bad ones! They gave the right answer but were

> inconvenient. After some fumbling, I rearranged to formula to 700 /

> h^2 * m. Much better. Set hairline to 700 on A, set inches on C to

> hairline, set hairline to pounds on B, read BMI on A.

>

> In some slide rule problems, values must be set on the correct half of A

> or B, but in this case it doesn't matter. Slide movement is less if you

> set 700 on the right half of A.

>

> This calculation may be good to remember when someone asks you what a

> slide rule can do. It demonstrates chained operations (even division by

> a square) in a real world problem, where all practical accuracy is

> easily attained on a 6 inch rule. No need for a BMI calculator on the

> Web when you have a slipstick. In fact, it's better than a calculator.

> Once the slide is set for height, the relation between BMI and weight is

> visible at once on A and B.

>

> On a slide rule with a double length root scale instead of A and B (like

> the Pickett N4), the solution is different: 1) hairline to inches on

> root scale, 2) 700 on C to hairline, 3) hairline to pounds on D, 4) read

> BMI on C at hairline.

>

> --

> I filter out messages with attachments or HTML.

>

>

>

> ------------------------------------

>

> Yahoo! Groups Links

>

>

> - View SourceHi to all,

Nomograms for figuring an amazing number of things exist in healthcare....

BMI calcs, most likely genotypes (pardon my interest in what unit of blood is MOST likely to be compatible with you), and various other calculations are routinely used in healthcare.

So....when your MD replies to your question(s), depending on his/her age you may receive a blank stare/iinteresting response/whipping out the "slide rule" as your reply.

41 years in healthcare...but...my most recent thing I am dealing with is my sister's "score" for her candidacy for a Liver tx (transplant).

Many calcs can be distilled down to a VERY simple cardboard calc that does the calculation for us/you that you wish to derive. A/B/CI/LL1/LL2 scales? Other scales?? The nomogram/aka cardboard rule has "figured" it out.

Thanks all,

Mike Coover

To: sliderule@yahoogroups.com

From: ccatt10@...

Date: Thu, 10 May 2012 22:42:11 +1000

Subject: SR BMI (body mass index) calculation

Next time you visit your physician, you might ask if one of the numerous salesmen who make the rounds of such establishments has left him with any surplus slide rules for calculating BMI, or any of the other indicators of the problems to which our flesh is heir. You may discover a source of new rules!

Cyril

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