To a European, 40 degrees is fecking scorching. -10 is fecking cold. Europeans don't wander around wondering if it's really cold or not because they're not using the F scale. 40 to them means just what 105 would mean to you. The centigrade scale was invented to put temperatures in terms of water. 100 equals boiling, 0 equals freezing. I tend to convert all temperatures in my head to both C and F depending which one I get first. For a benchmark, 37 is body temperature.
As far as the distance- tens are much more sensible to work with. Anybody can count in tens, hundreds, thousands. Not quite as easy to multiply times 5,280 or 1,760 or 36 or twelve.
The US military uses metric for distance- because it's smarter. I try not to read a whole lot more into it than that.
You're never going to have to worry about losing the various scales of measure we use because it would be much too costly for the US to retool. You'll be able to go on using measures based upon how far a Roman soldier could march etc until you die. In the UK, they do you one better. They measure human weight in stone. I still don't how much I weigh in stone- probably never will.
I find it amazing now that we actually went through a period of coehersive conversion to the metric system here in the US. Remember back in the 70s', I think it was, Carter was in office and we were going to all convert to the metric system within the span of just a few years. It would save buillions and buillllions of dinero because nobody would have to do any conversion any more.
In the 1970's there was a major effort to increase the use of the metric system, and Congress passed the Metric Conversion Act of 1975 to speed this process along. However, American consumers generally rejected the use of metric units for highway distances, weather reports, and other common measurements, so little was accomplished except for the encouragement of faster metric conversion in various scientific and technical fields. Interesting website...http://www.unc.edu/~rowlett/units/usmetric.html
All I know is I've dropped a few "stones" during this summer! Probably enough to make a boulder.
I fully comprehend the metric system and the Celsius scale but I still prefer the British Imperial system of weights and measures and I hope we never change.
I like my miles and inches and it will never sound right having a speed limit of 90 kilometers per hour or a snowstorm with 40 centimeters of snow. Likewise, I like my Fahrenheit. You do get a more accurate sense of how warm or cold it is with Fahrenheit simply because the scale is larger.
As for stones, well the British can keep their stones.