0 A short introduction to the metric system

We do use the metric system, or, more specifically, the Systeme Internationale, in doing science.  This causes no grief for any countries outside the US.  But about half my readers are in the US, so there is a constant issue about using the scientific units to talk about scientific topics.  (I'm sufficiently native that when discussing non-scientific topics, I do normally use feet/fathoms/rods/miles/....)

For the use of readers who tend to freeze when seeing metric units, here is a quick and dirty guide.  Emphasis on quick and dirty.  It will not be accurate, but it will give you the right general sense.  Good enough, at least, for Science Jabberwocky purposes.  It should also do for the non-US readers who are baffled when I use only the Imperial units.  (I try to avoid that, but probably lapse.)



Distance:
1 inch = 2 cm (centimeters)
1 meter = 1 yard = 3 feet
1 kilometer  = 0.5 miles
1 cm = 0.5 inches
1 mile = 2 kilometers


Temperature:
0 C = 32 F = freezing
10 C = 50 F = jacket weather
20 C = 68 F = room temperature
30 C = 86 F = hot weather
37 C = 98.6 F = body temperature
40 C = 104 F = blistering heat
-40 C = -40 F

Volumes:
1 liter = 1 quart
4 liters = 1 gallon

Mass/volume:
1 kg = 2 pounds
5 g = 1 tsp (water)
1 kg = 1 liter (water)

Speed:
1 meter/second (m/s) = 2 mph

I stress, these are not accurate figures (except for the temperatures).  If you want accurate, you should be working with scientific units in the first place.  Failing that, be using a resource that has the full precision conversions.  1 meter is actually 39.37 inches, not the 36 listed above.  The worst approximation is between mile and km.  1 mile = 1.60934 km, not 2.