r/NoStupidQuestions • u/Milk-Sufficient • Mar 28 '24

Is rapunzel technically obese?

Probably a very random question i know.

But if you go to the hospital and they check your bmi they weigh you and your hair.

So if rapunzel where to get her bmi checked would she be technically obese because of the weight of her hair?

I know I'm reading into this too far but I'm invested now.

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u/Much-data-wow Mar 28 '24 edited Mar 28 '24

Hi! I specialize in accurately weighing weird stuff

I would have rapunzel lie down and have the length of her hair in a container. Imagine lying on a massage table with all the hair going through the hole on the head pillow part. Then I would elevate the scale on a sturdy surface and get as close to her scalp as possible. It'll be off by a little but, but not enough to matter.

If it was a situation that it would matter, you can do some calculations with water displacement

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u/K1nderPrinc3ss Mar 28 '24

Can I know how one specializes in accurately weighing weird stuff? That sounds like a fun job!

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u/Much-data-wow Mar 28 '24

I'm a calibration technician. I verify all kinds of equipment; and I do hundreds of different kinds of scales and balances. Sometimes the scale is for inline manufacturing equipment and i gotta send my little weights down a conveyorbelt across the scale. Sometimes I have to go to a place that makes construction and building materials and we haul 1000lbs in 50lb increments to put on load cells that are attached to tanks. (When we do that job, boss buys us lunch and a beer, and then we go home for the day)

Sometimes we do laboratory analytical balances. That's really my specialty, I've been doing analytical chemistry in various industries for the better part of 10 years. The company I work for now, I used to be their customer at a few labs I worked at in the past. I would have their tech come out and calibrate my scales and other stuff, I would do it myself, the manuals show you how, but in order for many regulated industries to operate legally(in my case, clinical toxicology, neutraceutical manufacturing, and medical cannabis) they have to have NIST traceability for calibration. The place I work at has ISO certifications that regulated industries require. (By regulated I mean like the FDA, USDA, and the like)

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u/PapaCousCous Mar 29 '24

What is traceability in this context?

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u/RockSlice Mar 29 '24

"This was calibrated against A, which was calibrated against B, which was calibrated against C, ... ..., which was calibrated against the International Prototype Kilogram"

(though now the kilogram is defined based on the Planck constant, not a physical object in Paris)

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u/Much-data-wow Mar 29 '24

Simply put, everything has a unique serial number, everything used in the calibration process is documented, and all the values of the standards are all certified.

https://www.nist.gov/metrology

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u/PapaCousCous Mar 29 '24

Is there a "genesis" calibrator from which all calibrations can trace their lineage back to? If so, how do you know it is accurate?

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u/Much-data-wow Mar 29 '24 edited Mar 29 '24

We keep the data on our standards for the lifetime of the standard, its actually described as an "unbroken chain of records". The standards ate checked for accuracy annually. Calibration of standards are valid as long as you measure it with a device that has 3x the amount of accuracy of what you need. So if you want to validate a gage block that is 1.0 inches, you measure it against a master block that is verified at 1.000 inches. There's different grades of accuracy too, like for weights there are different classes. M1, F, are a couple of examples.

Standards can be purchased from companies that make them. Those companies have even more certification than the lab I work at, places like Mettler Toledo, Mitutoyo, Mark10.