A minute is a Nautical Mile (6000) feet in latitude. ( 100 feet per second) Latitude times the COS of the latitude for longitude. (At 33N = 1 second of longitude = 84 feet) Try that in kilometers! Guess your GPS will do those things for you. FYI: A grid square is only square at 60 degrees of latitude. COS = 0.5
And who on this side of the planer is at 60 degrees? Maybe a few seals and whales LOL Conversion between degrees and distance is not required much these days, with GPS and good maps. Nautical measurements are still used here in any case, in meteorology for example (wind speed is in km/h and knots).
On the other hand many caculations are simplified with metrics, wavelength for example. Amps, Volts, Farrads, Henerys, Ohms, Frequency, and Watts are same in metric and need no conversion.Grams, Litres and Meters require developing a feel. I can visualize an inch, not 3 cm ? I can feel an ounce, but not a gram, besides a pint is a pound of water! Is a litre of water a Kilogram?
3cm, dat's a little less than 1 1/4" ;) And a litre of water has 1kg mass (at 4 degrees Centigrade - the temperature at which the density of water is maximum).
73 de VK3JED http://vkradio.com