why don't people say mega meters

joel_feila@lemmy.world to Showerthoughts@lemmy.world – 164 points –

How come people say 5,000 km and not 5 Mm?
why not just say millions of meters or Mega meters?

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weirdly enough SI unit for mass is kg not grams

I've always found that strange. I guess a kilogram is a lot closer to "human scale" than a gram, maybe that's why they picked it.

yeah humans do really need a small, inch and cm, a medium, meter and feet, and a big, mile and km.

SI also does meter instead of cm, so it overall checks out.

Having meter as a base unit makes more sense than kg because meter lacks any prefix.

But that is like a giant difference in what they usually measure

My physics teacher once told us that this was due to the influence of disciplines that calculate with huge masses, say in astrophysics the weight of a planet or the the amount of oxygen within it. Don't know how much of it is true but the basic tenet of everyone preferring the numbers that they work with on a daily basis having as few prefixes as possible as it makes mentally handling and remembering them easier.