Science that makes you cringe

[Kim]

Get shot in a movie, find someone to stitch up entry and exit wounds and you're good to go. Everything in between is just ballistic gel, right?

Movie gunshots are only fatal when delivered by a very small gun with an improbably large amount of ammunition.

[spesh]

Anyway, here's another that I read recently. It's from a short story by Hemingway. I can't find the exact quote now but he described a gun as "having a muzzle velocity of two tons".

I went for the novel and radical approach of using a search engine and Googled for "hemingway getting muzzle velocity units wrong" - the third result on the first page was a PDF of Hemingway's short stories, wherein I established that Hemingway gets it wrong in "The Short Happy Life of Francis Macomber".

Macomber did not know how the lion had felt before he started his rush, nor during it when the unbelievable smash of the .505 with a muzzle velocity of two tons had hit him in the mouth, nor what kept him coming after that, when the second ripping crash had smashed his hind quarters and he had come crawling on toward the crashing, blasting thing that had destroyed him

See page 28 of: https://antilogicalism.com/wp-content/uploads/2018/04/hemingway.pdf

Looking up .505 cartridges led me to the Wiki page on the .505 Gibbs, designed for hunting dangerous game in tropical environments:

The cartridge's claim to fame was its use by the fictional character, Robert Wilson, the hunter of Ernest Hemingway's short story "The Short Happy Life of Francis Macomber".

The wiki page for the cartridge suggests a typical muzzle velocity of 2,100-2,300 ft/s (640-700 m/s) - how the hell Hemingway gets from that to two tons is anyone's guess!

I think Hemingway knew about guns

Hmmm... if he did, he'd use the correct units of measurement.

and this is probably the way gun people talk

No, non, nein, nyet and fucking nope, they wouldn't if they knew what they were talking about. They'd use the correct unit of measurement.

(with the actual mass of the bullet being a known factor).

Mass only comes into it someone is talking about muzzle energy, which is the kinetic energy (E_k) of a projectile as it leaves the gun barrel. Kinetic energy would be measured either in foot-pounds force or in joules.

But as E_k = 0.5 x mv², where m is mass and v is velocity, the fact that it is proportional to the square of the velocity should be a clue as to what is a bigger factor.

[Kim]

The wiki page for the cartridge suggests a typical muzzle velocity of 2,100-2,300 ft/s (640-700 m/s) - how the hell Hemingway gets from that to two tons is anyone's guess!

I expect you have to divide by 12 Parsecs...

[perpetual dan]

It’s a bit late for maths, but could two tons be about the pressure that’s causing the velocity?

[spesh]

It’s a bit late for maths, but could two tons be about the pressure that’s causing the velocity?

What's pressure measured in, though? 

I think Kim's closest to the mark with her Kessel Run reference, in that Hemingway either got his units mixed up, or he pulled the "two tons" figure from his backside.

And frankly, I've wasted enough time on this already...

[Mr Larrington]

The wiki page for the cartridge suggests a typical muzzle velocity of 2,100-2,300 ft/s (640-700 m/s) - how the hell Hemingway gets from that to two tons is anyone's guess!

I expect you have to divide by 12 Parsecs...

What’s that in double-decker buses/Olympic swimming pools/Waleses?

[Asterix, the former Gaul.]

Anyway, here's another that I read recently. It's from a short story by Hemingway. I can't find the exact quote now but he described a gun as "having a muzzle velocity of two tons".

I went for the novel and radical approach of using a search engine and Googled for "hemingway getting muzzle velocity units wrong" - the third result on the first page was a PDF of Hemingway's short stories, wherein I established that Hemingway gets it wrong in "The Short Happy Life of Francis Macomber".

Macomber did not know how the lion had felt before he started his rush, nor during it when the unbelievable smash of the .505 with a muzzle velocity of two tons had hit him in the mouth, nor what kept him coming after that, when the second ripping crash had smashed his hind quarters and he had come crawling on toward the crashing, blasting thing that had destroyed him

See page 28 of: https://antilogicalism.com/wp-content/uploads/2018/04/hemingway.pdf

Looking up .505 cartridges led me to the Wiki page on the .505 Gibbs, designed for hunting dangerous game in tropical environments:

The cartridge's claim to fame was its use by the fictional character, Robert Wilson, the hunter of Ernest Hemingway's short story "The Short Happy Life of Francis Macomber".

The wiki page for the cartridge suggests a typical muzzle velocity of 2,100-2,300 ft/s (640-700 m/s) - how the hell Hemingway gets from that to two tons is anyone's guess!

I think Hemingway knew about guns

Hmmm... if he did, he'd use the correct units of measurement.

and this is probably the way gun people talk

No, non, nein, nyet and fucking nope, they wouldn't if they knew what they were talking about. They'd use the correct unit of measurement.

(with the actual mass of the bullet being a known factor).

Mass only comes into it someone is talking about muzzle energy, which is the kinetic energy (E_k) of a projectile as it leaves the gun barrel. Kinetic energy would be measured either in foot-pounds force or in joules.

But as E_k = 0.5 x mv², where m is mass and v is velocity, the fact that it is proportional to the square of the velocity should be a clue as to what is a bigger factor.

When being taught to use a .303 at Bisley our army instructor said that the pressure inside the breech on discharge was 41 tons psi.  The thing certainly had a heck of kick.

[perpetual dan]

It’s a bit late for maths, but could two tons be about the pressure that’s causing the velocity?

What's pressure measured in, though? 

I think Kim's closest to the mark with her Kessel Run reference, in that Hemingway either got his units mixed up, or he pulled the "two tons" figure from his backside.

And frankly, I've wasted enough time on this already...

Fair point
Pressure “when” left for extra marks maybe?

[Cudzoziemiec]

What Spesh said. At least, that was the story I read. My sympathy is with the buffalo.

As for Hemingway knowing about guns, I was thinking that jargon will often use terms which are not technically correct but refer to additional assumed knowledge. Cyclists' "gear inches" might be a case in point. You don't need to know anything about guns to know that velocity isn't measured in tons. (I'm also faintly suspicious of the accuracy of Mrs Macomber's shooting, but as IKNAG I'll let it be... )

[Kim]

This sort of confusion can be avoided by using unitless jargon.  Lighting techs seem to make it an art form: "4 250s at 100 on 3" sort of thing.

[Cudzoziemiec]

I suspect those are assumed units rather than truly unitless...

As a writer, Hemingway was subject to Editors and even Translators as well as whatever Knowledge he may or not have had. "The unbelievable smash of the .505 with its 525-grain bullet at a muzzle velocity of 2,300 feet per second" "No, Mr Hemingway, you can't write that! The readers won't like it! Let's just say a muzzle velocity of, ooh, four tons. That gets the idea across, don't you think?" "But..." "Too much? You're right, let's make it two tons."

And where do the Translators come in? Well, they don't so far, but I'm just wondering how they've translated it. Are those long, short or metric tons? Or have they mangled it into some other, maybe more sensible, unit, because all readers in language X are familiar with muzzle velocity in terms of goose wings per fortnight? And what are grains in any case?

[Mr Larrington]

A grain is 64.79891 milligrams, as any fule kno

[T42]

Reminds me of learning to drive, when the instructor told me gleefully that a rear-seat passenger without a seat-belt would hit me with a weight of seven tons in a crash.  Not a velocity, though.  Most people use velocity interchangeably with speed.  A ton used to mean a speed of 100 mph. Maybe it still does.  I've just been reading some Hemingway. You can tell.

[Cudzoziemiec]

So it did. "Doing a ton on the motorway" and so on. Right, a mile is 5280 feet, x 200 so 200 mph is 105,600 feet per hour. Divide by 3,600 = 293.3 feet per second. Hmm, that's not right either, unless (very likely) my arithmetic's wrong.

[Mr Larrington]

Seven point four foopball pitches per blue whale, then.

[Tim Hall]

Foyle's War last night was set just post war.  An amount of Urnanium was deemed to be missing from a thinly disguised Harwell. It (or "the isotopes") was transported around by the villains in a thermos flask.

The amount?
190 microgrammes.
That's a piece about <fx:back of envelope scribbling> 1 x 10^-11m^3. Or Very Tiny Indeed

[ravenbait]

Foyle's War last night was set just post war.  An amount of Urnanium was deemed to be missing from a thinly disguised Harwell. It (or "the isotopes") was transported around by the villains in a thermos flask.

The amount?
190 microgrammes.
That's a piece about <fx:back of envelope scribbling> 1 x 10^-11m^3. Or Very Tiny Indeed

11 cubic metres is A LOT. That would be 11 tonnes of water.

Clearly you use ascii notation differently from me

<fx: scientific calculator tapping>

Density of uranium is 19g per cubic centimetre or ml. 190 microgrammes (0.190/19) is 0.01ml. Random fact: average human tear volume is 6.2 +/- 2 µl, which means your uranium is <scribbles> about one and half tears. Give or take.

Sam

[spesh]

I read what Tim posted as 1x10^-11 m³ - I'd guess he's using ^ to denote superscript as a quick'n' dirty subsitute for messing around with formatting tags.

[Tim Hall]

Foyle's War last night was set just post war.  An amount of Urnanium was deemed to be missing from a thinly disguised Harwell. It (or "the isotopes") was transported around by the villains in a thermos flask.

The amount?
190 microgrammes.
That's a piece about <fx:back of envelope scribbling> 1 x 10^-11m^3. Or Very Tiny Indeed

11 cubic metres is A LOT. That would be 11 tonnes of water.

Clearly you use ascii notation differently from me

<fx: scientific calculator tapping>

Density of uranium is 19g per cubic centimetre or ml. 190 microgrammes (0.190/19) is 0.01ml. Random fact: average human tear volume is 6.2 +/- 2 µl, which means your uranium is <scribbles> about one and half tears. Give or take.

Sam

I more likely got lost in a maze of exponentials. Although I'd argue that 190 microgrammes isn't 0.19g, as your calcs suggest. Isn't it 0.00019g?, so the volume is 0.00001ml. Maybe.     

[ravenbait]

I more likely got lost in a maze of exponentials. Although I'd argue that 190 microgrammes isn't 0.19g, as your calcs suggest. Isn't it 0.00019g?, so the volume is 0.00001ml. Maybe.   

You are correct. I was distracted by the dog's farts (she has a dodgy tummy and yet insists on being in my office. I am dreading having to shoo her out in the event of a digestive incident).

So that's.... 0.1µl? It's too hot to think today. So you would fit 60 times the aforementioned amount of Foyle's uranium in a single human tear.

A thermos does seem overkill. Unless Foyle's uranium is related to red mercury, and is a special kind of uranium. Probably glows fluorescein green, stains the skin, and makes red blood cells look suspiciously like spirochaetes.

Sam

[Kim]

Yeabut the first rule of fissile material club is that you don't leave things lying around where they can occupy small volumes.  Normally that's in order to prevent unexpected criticality incidents, but it seems like equally sage advice if it's small enough that it risks being lost forever in the piles of the carpet should someone sneeze while handling it.

[perpetual dan]

I hope the tea lady uses a nice big urn, and doesn't make off with the flask by mistake, though at least a flask isn't going to get tidied into the bin by the cleaners like a small empty tin might.

[Pingu]

Lost in translation?


IMG_8611_01 by The Pingus, on Flickr

[SteveC]

Our kitchen scales will weigh in ml. I've always assumed they mean 'of water' and that it's just the same readings as g.

[Tim Hall]

From an E bike manufacturer's website:

This rear-drive motor, which is compatible with the disc brake, has a rated power of 750W and Max Power  of 1500W (48V*30ah= 1440W),

<Boggle>