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Old 2021-09-28, 23:02   #12
chalsall
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Quote:
Originally Posted by pinhodecarlos View Post
I would had said Pascal instead of pascal.
I know you're taking the piss there. And I smiled...

Audio doesn't have Capitalization. This is why Law is interpreted by Judges CASE insensitive.

Seriously.
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Old 2021-09-29, 01:33   #13
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I assume the notion of mileage being in square units (or inverse square units) is merely whimsical, and given with humorous intent. I like it.

Analyzing the artistry, it is a nice bit of subreption. The material fact being omitted is that in the phrase "miles per gallon," the word "gallon" is understood to mean "gallon of fuel." Motor vehicles, after all, run on fuel, not on units of cubic capacity. And in a vehicle capable of burning different types of fuel, the mileage will depend on which type of fuel it is using. Gasohol gives lower mpg than gasoline. Pure ethanol gives yet lower mpg.

As to whether distance per unit of fuel or fuel per unit distance is "better," better for what? One consideration is whether the figure is at or near a positive but not-too-huge whole number. I'm used to mpg, (distance per unit of fuel). But that's for passenger cars. That's usually at or near a number with 2 decimal digits. For something like a heavy tank, mpg is less than 1, maybe 0.6. Maybe even less if it's moving at top speed. For a heavy jet airliner, it might be 0.2 mpg. If mpg is a small fraction, gpm (fuel per unit of distance) might be more convenient.

I suppose you could instead use money spent on fuel per unit of time driving. This has the advantage of being a "dimensionless" number (the units cancel out) because, as everyone knows, time is money.

Last fiddled with by Dr Sardonicus on 2021-09-29 at 01:34 Reason: xingif optys
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Old 2021-09-29, 01:47   #14
retina
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Quote:
Originally Posted by Dr Sardonicus View Post
As to whether distance per unit of fuel or fuel per unit distance is "better," better for what?
Better for comparison I suppose. And, of course, larger values are always better than smaller values. Everyone knows that.

Those slow pokes in the Olympics can only manage ~10s for the 100m sprint. Pfft. I can do that easily. Indeed I can do 60s if I'm of the right frame of mind. Naturally 60s is six times better than 10s, so I would win.
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Old 2021-09-29, 20:18   #15
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Quote:
Originally Posted by chalsall View Post
As Musk recently said, "A pascal is what? A mouse fart?
Musk really ought to know better. 100 pascals = 1 hectopascal (hPa) = 1 millibar, so a pascal is one hundred-thousandth of roughly the atmospheric pressure on Earth at an altitude of 111 metres at 15 °C.
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Old 2021-09-30, 02:01   #16
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Quote:
Originally Posted by BudgieJane View Post
so a pascal is one hundred-thousandth of roughly the atmospheric pressure on Earth at an altitude of 111 metres at 15 °C.
So ... basically a mouse fart?
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Old 2021-09-30, 04:24   #17
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DuckDuckGo search on "pressure difference of a mouse fart" yielded https://castboolits.gunloads.com/sho...in-30-06/page2 Those mouse farts are nothing to sneeze at.

And https://www.menshealth.com/health/a1...4/fart-noises/ I suppose one could estimate pressure difference across the orifice using hot wire anemometry for velocity measurement and applying Bernoulli's law. Though the test subject may tolerate wheat flour dust doppler anemometry better. Imagine that grant proposal.

A pascal is 1N/m2. At 1gravity, ~9.8N/kg, 20g/mouse, that's 1N/m2 1000g /9.8N 1 house-mouse/20g =5.1mice/m2. Given their short lifespans and high metabolic rate, that's probably a lot of mouse farts/m2/day. And numerous little black rice.

Mean arterial pressure of conscious unsedated mice ~ 100mmHg (0.13 atm or 13KPa) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3115725/

Measured internal pressures in mice (antrum & duodenum) peak at ~10-20cmH2O
https://journals.physiology.org/doi/...pgi.90692.2008 page 3 fig 2

Last fiddled with by kriesel on 2021-09-30 at 04:56
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Old 2021-09-30, 06:26   #18
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If you guys don’t mind some teaching since I’m always learning something new on this forum let’s start using the units correctly. So it is not 100 Pascals but 100 Pascal, don’t use plural. Here on TV with regards to mentioning pressure in “bar” they always say “bars”, which also means “pubs”…lol
Another common mistake is KPa, it is kPa, lower case for the “k”. “K” is Kelvin for temperature. You can already see that if a unit is named by the founder it is capitalise letter.

Now a funny thing. Within Europe we use the SI system therefore when you see on the motorway or highway the speed limit sign of “70” we always relate to 70 km/h, from the Highway Code, but I always relate to the SI base unit which is m/s. Lol

Last fiddled with by Dr Sardonicus on 2021-09-30 at 13:01 Reason: xingif topsy
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Old 2021-09-30, 07:12   #19
kriesel
 
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Quote:
Originally Posted by pinhodecarlos View Post
Another common mistake is KPa, it is kPa, lower case for the “k”. “K” is Kelvin for temperature.
But 1MPa is 109mPa is it not?
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Old 2021-09-30, 08:46   #20
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All prefixes for something smaller or equal to 103 have a lower case letter, all above that have a capital letter. That's definitely the case for yocto (y) up to yotta (Y). I'm ommitting something like ångström here.
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Old 2021-09-30, 13:27   #21
Dr Sardonicus
 
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I note that WRT mouse farts, the relevant kind of pressure is gauge pressure, the difference in pressure between inside and outside. And when it comes to breaking wind, I am skeptical that a pressure difference of a hundred thousandth of an atmosphere is going to get the job done.
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Old 2021-09-30, 14:01   #22
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Quote:
Originally Posted by pinhodecarlos View Post
If you guys don’t mind some teaching since I’m always learning something new on this forum let’s start using the units correctly. So it is not 100 Pascals but 100 Pascal, don’t use plural.
So should on say "I drank 250 milliliter of gin last night!"? Or "My daughter was able to crawl 4 meter from her crib to the parlor."? Should not those units be plural?
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