Bit on the news about the Pacific Ocean rowers and it was all about knots and nautical miles and I thought why do we have these measurement which most of us cannot relate to. We know what a mile is and what a metre is. Personally I cannot imagine a kilometre but I have never really needed to use that measurement. Though I do note with some amusement that the BBC seems to talk in kilometres when as far as I know here in the UK road distance is invariable measured in miles. But I can sort of get my head around kilometres. But knots and nautical miles make n osense. I know what they are as I have just Googled both but I do not know why we went this route in the first place. Keep it simple, if possible, please as I am not getting any younger.
Legacy. Knots were used as a speed measurements at sea long before codified unit systems, so still get used because changing would be a huge pain in the arse. The Nautical Mile is still useful because it's (ostensibly) 1 Minute of Arc around the Earth's circumference, which makes converting between coordinates on a map and linear distances a lot easier. Historically, 'Mile' has referred to such a bizarre plethora of different distances that is you're looking at data more than a couple of hundred years old you need to do some digging to figure out which mile is actually being used! Personally, I know how long a meter and kilometer are, and have no intuitive idea how long a mile or x00 feet is. Finally finishing metrication across the UK would be a fantastic improvement, but it seems that will have to wait for all the stick-in-de-mud politicians to die off before it can happen.
The only problem with that, is that stick-in-the-mud politicians tend to breed more stick-in-the-mud politicians.
If you look there are some road signs in the UK that are in meters. For example the ones leading up to a junction on the motorway. The height sign on bridges shows the height in meters first as well now.
I adapted my brain to kilometres, but only when traveling at a certain speed. Above a given threshold then it's miles all the way? Explain? Okay, I will. OS Maps are arranged out with nice little 1km grid lines, so when planning a walk/run/cycle it's nice and easy to use kilometres as that's what the maps use. So if I'm not in a car, then I think in kilometres. But when in a car, traveling at 70MPH and I have 140 miles to go... ...Then I know I'm on a road with too many speed cameras. 70MPH indeed!
Nautical miles and Knots are still prevalent due to it matching up to the latitude and longitudinal minutes, hours and makes plotting navigation easier.
its much the same in quite a few things tbh atmospheric Height is usually measured in feet ( aircraft cruising altitude, building / mountain heights ) and speed is Knots / MPH usually and just to confuse people runways are measured in meters XD you also have weight of aircraft measured in KG, but thrust of engines in pounds
The unit knots comes from how they used to calculated the speed in ye olden days. They would throw a large bouy overboard with a rope attached which had knots tied into it a foot (or possibly yard) apart, then they would count how many knots would pass through their hands in a minute to get their speed.
A ripe what Whereas I knew pretty much how it was calculated I was wondering why. Though if you think about it calculating mph on water would be tricky in those days.
That would be the log. The line was 100 fathoms long (600 feet, 183 metres), with knots every 47 feet 4 inches with a 28-second glass, or 50 feet 9 inches with a 30-second glass. The speed read from this would be recorded in the log-book. Hence the name "log-book".
That depends, engines made by the Americans give their quoted thrust in pounds, everyone else quotes rated thrust in KiloNewtons.
I studied science at university so if I have to do any calculations I tend to convert everything into SI units and go from there.
