Funny how 'km' has become so commonplace we forget we can write '1 Mm' (megameter).
Once you are in the realm of science and engineering, you are more likely to encounter scientific notation anyways, e.g. 2.99 x 10^8 m instead of 299 Mm.
I think power is the only metric unit I've seen where the common unit also often follows metric notations. 1 kW, MW, GW, TW.
Yeah, I do this a ton myself. I apologize.
The fact that kg is the base unit does not make much sense except for historical reasons when the choice was made. A very bad choice if you ask me.
Then again it's not only weird unit we have, dB is the other one. Ofc, units are nicer to handle, but still... Not that bell isn't weird unit anyway.
And, again the French way, it is not possible to see them!
This isaid, the mass base unit in SI is really the kg, even if g would be natural (and indeed people will say 1 g instead of 1 millikilogram).
I was always annoyed by kg being the base unit (and I had to drag this suffering throughout my PhD in physics) but this thread opened my eyes on the possibility to use "compensating" prefixes on the kg (millikilogram to say gram) - it is a shame I did not think about that before to drive everyone crazy :)
You might just not recognize them as such.
Ampere, Volt, Ohm, Tesla, Newton, Pascal, Hertz, Joule, ... are all SI units or directly derived from SI units and used with SI-prefixes regularily.
https://www.theregister.com/Design/page/reg-standards-conver...
If you want to pick a gripe why do we measure capacity in charge per unit of time times hour, rather than MJ?
On the other hand, ratings within a group of products are usually done without a prefix change. Perhaps because of defective sorting algorithms, which would e.g. place a 1.7 kV device at the end of the list, while putting a 1500 V device first. That's probably why you see e.g. 4700 µF instead of 4.7 mF as well, though sometimes the latter is used.
> If you want to pick a gripe why do we measure capacity in charge per unit of time times hour, rather than MJ?
They're equivalent, it's just that writing Wh makes it very clear that you can divide this figure by some discharge power and get the approximate discharge duration. OTOH, an EE likely knows [power W] * [time s] = [energy J] anyway.
[0] Example: https://www.amazon.com/10000mAh-Portable-Charger-Stylish-Com...
If you want to get even crazier, what about fuel economy? Using miles per gallon (or km/l) can also be simplified to reciprocal area, so 40 mpg is just 1.7e7 m^-2. For an electric car you can change 250 miles per 100 kWh to the more perfect representation 0.001 s^2 /(kg m).
Some say "but Wh is easier to understand". My counter-guess is that the people who have a hard time understanding J don't actually need to. They just need to compare one value to another, and then the unit doesn't matter (had we used J to start with).