Arithmetic that makes you cringe

[hellymedic]

A knot is a nautical mile per hour.

A nautical mile (1852 metres) is a bit more than a statute mile (1609 metres).

[Giraffe]

The pedant in me dislikes knots per hour.

Thanks for that, I know f-all about boats but my first through on reading that was "isn't knots a unit of speed?"  (I believe due to the expression "travelling at a rate of knots" which implies that whatever a knot is, it measure speed).

A rate of knots would be acceleration.

[ravenbait]

A rate of knots would be acceleration.

Does the phrase not date back to the time when speed was determined by counting knots in a rope attached to a drag that was put out the stern of a ship? So that would be "rate of knots counted per 30 seconds."

Sam

[T42]

A rate of knots would be acceleration.

Does the phrase not date back to the time when speed was determined by counting knots in a rope attached to a drag that was put out the stern of a ship? So that would be "rate of knots counted per 30 seconds."

Sam

Probably for something like "per one turn of the small glass". It's probably OK to use if if you're still timing things other than eggs with sand-glasses, but most of us have moved on.

"Knots per hour" is just bloody ignorant (and/or BBC standard).

[hatler]

A rate of knots would be acceleration.

Does the phrase not date back to the time when speed was determined by counting knots in a rope attached to a drag that was put out the stern of a ship? So that would be "rate of knots counted per 30 seconds."

Sam

I've done that.  With one of these. Bizarrely, for reasons I can't remember, the sand glass counts to 14 seconds. If I could be bothered I'd sit down and work it out. It probably means the knots in the line are x fathoms apart.

[ravenbait]

Probably for something like "per one turn of the small glass". It's probably OK to use if if you're still timing things other than eggs with sand-glasses, but most of us have moved on.

Lots of idioms remain in use after people no longer do the thing that coined the phrase.  We no longer use guns in naval warfare that have an accurate range best described as "near enough to piss on", but we still use the phrase "a long shot" to refer to something being a slim chance. And at least some of us know that the phrase is "toe the line" (not "tow the line"), and nobody is expected to line up barefoot on deck any more.

"Knots per hour" is just bloody ignorant (and/or BBC standard).

Completely agree.

Sam

[PeteB99]

A rate of knots would be acceleration.

Does the phrase not date back to the time when speed was determined by counting knots in a rope attached to a drag that was put out the stern of a ship? So that would be "rate of knots counted per 30 seconds."

Sam

I've done that.  With one of these. Bizarrely, for reasons I can't remember, the sand glass counts to 14 seconds. If I could be bothered I'd sit down and work it out. It probably means the knots in the line are x fathoms apart.

Correct. Although the usual glass used was a 28 seconds one with the knots 7 fathoms apart.

That's assuming my memory is still functioning

[hatler]

Ooo. Possibly it was 28 seconds. It's a while since I last did this.

[PeteB99]

I only ever did it once as an exercise in making a chip log in the sea scouts. I'm pretty sure the antique timer glass they gave us to work with was 28 secs.We had to build the rest with assorted bits of wood a long line and a measured fathom stick. It worked quite well when we tested it.

[Pingu]

more than 53,969

So maybe 53,970?

[Pingu]

Each system will consist of approximately two 25-centimeter (10in) telescopes with a camera

https://www.theguardian.com/science/2021/jul/27/galileo-project-search-signs-extraterrestrial-technology

[Giraffe]

This could also be under crazy foreigners: in Utah some contenders for a Darwin Award are hanging hammocks from HV lines; the sheriff warn "...that power lines carry 75,000 kilovolts of power and that the energy can jump between lines,...".
75MV!!! as power?

[T42]

Power has been used colloquially to mean electricity for years, probably for over a century.

[Feanor]

I'm OK with that too.
I parse it as the lines are carrying power, at a voltage of 75 kV.

[Kim]

It's the "volts of power" that throws me more than the use of 'power' to mean 'electricity'.  "Carrying power at 75kV" would be fine, but I'm generally of the opinion that once you mention Volts, Amperes or Watts, you really ought to use them correctly.

But since this is the cringeworthy aritmetic thread, not the grammar one, the real error is that they say "75,000 kilovolts", when they mean 75 kilovolts / 75,000 volts.  If it were 75MV it would seriously hamper the hammock-hanging efforts, on account of having reduced everything in the vicinity to plasma.  Simple typo that would easily sneak past a proofreader with limited knowledge of electricity.

[Cudzoziemiec]

It could have slipped past a proofreader but more likely it never met one. Anyway, I'd parse the whole thing as "We need to stop stupid people doing dangerous things. The technical details don't matter (if they understood them, they wouldn't be doing these things in the first place), we just need to emphasize the danger."

[Diver300]

If anyone hasn't worked out the problem here, the concentration for 1000 litres is probably correct, but should go up for smaller quantities of water and down for larger quantities.

[chrisbainbridge]

BBC reporter stating that temperature of 48degC in Sicily is half way to boiling point.
No, just no!

[Kim]

Of 5-methoxy-2-tetralone, presumably...   

[Basil]

BBC reporter stating that temperature of 48degC in Sicily is half way to boiling point.
No, just no!

Ah Chris beat me to it.
I guess half way to boiling point would be roughly  -186.575c.

[Giraffe]

Ordnance Survey's Tour 3 map of Lake District:
1:110 000 scale             1 cm to 1 km - 1 inch to 1¾ miles.
Explains 'friendly fire'.

[Cudzoziemiec]

BBC reporter stating that temperature of 48degC in Sicily is half way to boiling point.
No, just no!

Alternatively, it's the triumph or arithmetic over physics.

[Lightning Phil]

BBC reporter stating that temperature of 48degC in Sicily is half way to boiling point.
No, just no!

Alternatively, it's the triumph or arithmetic over physics.

Halfway between freezing and boiling point of water will be what they meant.

[ravenbait]

Ordnance Survey's Tour 3 map of Lake District:
1:110 000 scale             1 cm to 1 km - 1 inch to 1¾ miles.
Explains 'friendly fire'.

Makes me think of the house in House of Leaves.

Sam

[ian]

BBC reporter stating that temperature of 48degC in Sicily is half way to boiling point.
No, just no!

Alternatively, it's the triumph or arithmetic over physics.

Halfway between freezing and boiling point of water will be what they meant.

That's how I read it (and I'm sure most other readers).