howardang Posted October 8, 2020 Report Share Posted October 8, 2020 35 minutes ago, Captain Pegg said: Highly debatable that a knot isn’t metric. Don’t be confused by the use of the term ‘mile’ in nautical mile. It’s got nothing to do with the imperial statute mile. A nautical mile is derived from the distance at the Earth’s surface of the chord between two radials separated by an angle of one minute at the Earth’s centre. Degrees, minutes and seconds while not SI units are recognised measures under that system. A nautical mile is internationally acknowledged as being exactly 1852 metres having been standardised to the SI unit for length. Therefore a knot is 1.852 km/hour. And back to topic, can I point out that the term “shiny boat” is as much metaphorical as it is literal. Not all boats that shine are ‘shiny boats’. JP Never mind these new fangled metre things... a Nautical mile is, and will always be 6080 feet, otherwise I'll get lost! Howard 3 Link to comment Share on other sites More sharing options...
Alan de Enfield Posted October 8, 2020 Report Share Posted October 8, 2020 46 minutes ago, Captain Pegg said: A nautical mile is internationally acknowledged as being exactly 1852 metres having been standardised to the SI unit for length. Therefore a knot is 1.852 km/hour. Strange that the NM is shown as not being an SI unit : A nautical mile is a unit of measurement used in air, marine, and space navigation, and for the definition of territorial waters. Historically, it was defined as one minute of latitude along any line of longitude. Today the international nautical mile is defined as exactly 1852 metres. Unit of: Length 1 M, NM, or nmi in: is equal to Unit system: Non-SI unit Statute mile: ≈1.15 Metre: 1852 Symbol: M, NM, or nmi Foot: ≈6076 Link to comment Share on other sites More sharing options...
Scholar Gypsy Posted October 8, 2020 Report Share Posted October 8, 2020 36 minutes ago, Alan de Enfield said: Strange that the NM is shown as not being an SI unit : A nautical mile is a unit of measurement used in air, marine, and space navigation, and for the definition of territorial waters. Historically, it was defined as one minute of latitude along any line of longitude. Today the international nautical mile is defined as exactly 1852 metres. Unit of: Length 1 M, NM, or nmi in: is equal to Unit system: Non-SI unit Statute mile: ≈1.15 Metre: 1852 Symbol: M, NM, or nmi Foot: ≈6076 Oh dear, I am going to have to upgrade my Excel spreadsheet that I use to compute speeds from a series of readings (time, lat, long) from the digital log on my phone (Mxmariner). At the moment I am assuming the earth is a perfect sphere .... Link to comment Share on other sites More sharing options...
BlueStringPudding Posted October 8, 2020 Report Share Posted October 8, 2020 On 06/10/2020 at 14:47, mark99 said: The worst/best snack for me was Waitrose 'mignons morceaux' which were basically heavily garlic'ed croutons. They were so darn more-ish - very difficult to stop eating - only 30 mins after demolishing, I stunk of garlic and mouth felt wrecked. As well as ruined taste buds for 6 hours. Not to mention burps! They have been discontinued.... fortunately I think. That takes me back! My mum used to love those. I would try to snaffle some from her when I was a kid. We called them Minging Morso's ? You would do garlic burps for a week after eating them. 3 Link to comment Share on other sites More sharing options...
Machpoint005 Posted October 8, 2020 Report Share Posted October 8, 2020 (edited) 3 hours ago, Flyboy said: Knots are not metric, they're nautical miles per hour. Since a nautical mile is (roughly, still) one minute of arc along any line of longitude, it is related directly to the size of the globe and is especially useful for lumpy water navigation. It is neither imperial nor metric. A nautical mile just happens to be of similar length to a statute mile. We inland boaters navigate by mileposts, so it makes sense to measure our speed in mph. Edited October 8, 2020 by Machpoint005 Link to comment Share on other sites More sharing options...
Jen-in-Wellies Posted October 8, 2020 Report Share Posted October 8, 2020 46 minutes ago, Scholar Gypsy said: Oh dear, I am going to have to upgrade my Excel spreadsheet that I use to compute speeds from a series of readings (time, lat, long) from the digital log on my phone (Mxmariner). At the moment I am assuming the earth is a perfect sphere .... As long as you don't travel more than 65,535 nautical miles your Excel spreadsheet will work fine. You don't work for Serco on Test and Trace by any chance? Jen ? Link to comment Share on other sites More sharing options...
mark99 Posted October 8, 2020 Report Share Posted October 8, 2020 Just pretend you are measuring distance in Newton Metres. SI compliant. Link to comment Share on other sites More sharing options...
Scholar Gypsy Posted October 8, 2020 Report Share Posted October 8, 2020 29 minutes ago, Jen-in-Wellies said: As long as you don't travel more than 65,535 nautical miles your Excel spreadsheet will work fine. You don't work for Serco on Test and Trace by any chance? Jen ? Thank you, I will bear that in mind! No, I don't work for Serco. Whenever anyone worked up a spreadsheet for me I always asked what consistency checks they had built in. Occasionally this got a blank look, which rang alarm bells. For example a column of figures, with several sub-totals and then a grand total. It's very easy to get this wrong (and especially so if you add extra rows later on and forget to amend the sub-total formula), and very easy to write a consistency check for the grand total. I also spent a lot of time on implementing this excellent report (which followed the West Coast franchising saga) in my bit of the bureaucracy, which should be read by anyone who runs models or algorithms. https://www.gov.uk/government/publications/review-of-quality-assurance-of-government-models In the test and trace context, I am just gobsmacked that nobody thought to build in a daily (and independent) check that the number of rows of data imported into the master database was equal to the number sent in by the various labs. It's just basic accounting. 2 Link to comment Share on other sites More sharing options...
Jen-in-Wellies Posted October 8, 2020 Report Share Posted October 8, 2020 19 minutes ago, mark99 said: Just pretend you are measuring distance in Newton Metres. SI compliant. That's just crazy torque. ? 1 2 Link to comment Share on other sites More sharing options...
Machpoint005 Posted October 8, 2020 Report Share Posted October 8, 2020 36 minutes ago, mark99 said: Just pretend you are measuring distance in Newton Metres. SI compliant. Or time in parsecs? 1 Link to comment Share on other sites More sharing options...
Dyertribe Posted October 8, 2020 Report Share Posted October 8, 2020 2 hours ago, BlueStringPudding said: You would do garlic burps for a week after eating them. Worth it though! 1 Link to comment Share on other sites More sharing options...
WotEver Posted October 8, 2020 Report Share Posted October 8, 2020 4 hours ago, Captain Pegg said: A nautical mile is internationally acknowledged as being exactly 1852 metres having been standardised to the SI unit for length. Therefore a knot is 1.852 km/hour. So there you go... 65kph sounds much better than 40mph Link to comment Share on other sites More sharing options...
Loddon Posted October 8, 2020 Report Share Posted October 8, 2020 38 minutes ago, WotEver said: So there you go... 65kph sounds much better than 40mph Shouldn't that be 64.374 kilometres per hour Link to comment Share on other sites More sharing options...
ditchcrawler Posted October 8, 2020 Report Share Posted October 8, 2020 3 hours ago, Machpoint005 said: Since a nautical mile is (roughly, still) one minute of arc along any line of longitude, it is related directly to the size of the globe and is especially useful for lumpy water navigation. It is neither imperial nor metric. A nautical mile just happens to be of similar length to a statute mile. We inland boaters navigate by mileposts, so it makes sense to measure our speed in mph. But is the earth expanding or shrinking Link to comment Share on other sites More sharing options...
Machpoint005 Posted October 8, 2020 Report Share Posted October 8, 2020 42 minutes ago, Loddon said: Shouldn't that be 64.374 kilometres per hour Only if you know the speed in mph to the same precision. Link to comment Share on other sites More sharing options...
Popular Post Loddon Posted October 8, 2020 Popular Post Report Share Posted October 8, 2020 17 minutes ago, ditchcrawler said: But is the earth expanding or shrinking Just remember that you're standing on a planet that's evolving And revolving at 900 miles an hour. It's orbiting at 19 miles a second, so it's reckoned, The sun that is the source of all our power. Now the sun, and you and me, and all the stars that we can see, Are moving at a million miles a day, In the outer spiral arm, at 40, 000 miles an hour, Of a galaxy we call the Milky Way. 5 Link to comment Share on other sites More sharing options...
Flyboy Posted October 8, 2020 Report Share Posted October 8, 2020 2 minutes ago, Loddon said: Just remember that you're standing on a planet that's evolving And revolving at 900 miles an hour. It's orbiting at 19 miles a second, so it's reckoned, The sun that is the source of all our power. Now the sun, and you and me, and all the stars that we can see,Are moving at a million miles a day, In the outer spiral arm, at 40, 000 miles an hour, Of a galaxy we call the Milky Way. Careful, if the NBTA see this they won't need to untie their ropes at all and still claim they are travelling. 3 Link to comment Share on other sites More sharing options...
Tracy D'arth Posted October 8, 2020 Report Share Posted October 8, 2020 Question. Why does the earth, and as far as known all the planets in our little system, rotate? But the moon doesn't. The sun does, at different speeds at the poles compared with the equator.. Link to comment Share on other sites More sharing options...
Flyboy Posted October 8, 2020 Report Share Posted October 8, 2020 12 minutes ago, Tracy D'arth said: Question. Why does the earth, and as far as known all the planets in our little system, rotate? But the moon doesn't. The sun does, at different speeds at the poles compared with the equator.. The moon orbits the Earth once every 27.322 days. It also takes approximately 27 days for the moon to rotate once on its axis. As a result, the moon does not seem to be spinning but appears to observers from Earth to be keeping almost perfectly still. Scientists call this synchronous rotation. 1 Link to comment Share on other sites More sharing options...
alias Posted October 8, 2020 Report Share Posted October 8, 2020 15 minutes ago, Tracy D'arth said: Question. Why does the earth, and as far as known all the planets in our little system, rotate? But the moon doesn't. The sun does, at different speeds at the poles compared with the equator.. It does, otherwise you wouldn't see the same side from wherever you look on earth would you? Link to comment Share on other sites More sharing options...
Tracy D'arth Posted October 8, 2020 Report Share Posted October 8, 2020 1 minute ago, alias said: It does, otherwise you wouldn't see the same side from wherever you look on earth would you? 2 minutes ago, Flyboy said: The moon orbits the Earth once every 27.322 days. It also takes approximately 27 days for the moon to rotate once on its axis. As a result, the moon does not seem to be spinning but appears to observers from Earth to be keeping almost perfectly still. Scientists call this synchronous rotation. Not relative to the sun. Floyd worked it out, there is a Dark Side Of The Moon. Link to comment Share on other sites More sharing options...
alias Posted October 8, 2020 Report Share Posted October 8, 2020 (edited) 6 minutes ago, Tracy D'arth said: Not relative to the sun. Floyd worked it out, there is a Dark Side Of The Moon. Only figuratively. A new moon has the side we can't see opposite us facing away from us bathed in sunlight. Edited October 8, 2020 by alias Link to comment Share on other sites More sharing options...
roland elsdon Posted October 8, 2020 Report Share Posted October 8, 2020 (edited) Coming back to earth what was the initial post about again? Oh yes the OP set the controls for the heart of the sun. Edited October 8, 2020 by roland elsdon Typo Link to comment Share on other sites More sharing options...
Flyboy Posted October 8, 2020 Report Share Posted October 8, 2020 6 minutes ago, Tracy D'arth said: Not relative to the sun. Floyd worked it out, there is a Dark Side Of The Moon. You wanted to know if the moon rotated and I gave you the answer. You better tell NASA then, as this is from their website :- https://moon.nasa.gov/about/misconceptions/ Misconception The Moon does not rotate. Reality The Moon does spin on its axis, completing a rotation once every 27.3 days; the confusion is caused because it also takes the same period to orbit the Earth, so that it keeps the same side facing us. Link to comment Share on other sites More sharing options...
Arthur Marshall Posted October 8, 2020 Report Share Posted October 8, 2020 34 minutes ago, alias said: It does, otherwise you wouldn't see the same side from wherever you look on earth would you? Of course it doesn't. It's flat, like the Earth, so if it did it would get all thin and then get fat again. Oh. Link to comment Share on other sites More sharing options...
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