useless unit conversions
interesting relationships between quantities that will

*never*

come in handy


rhode island is almost exactly 4,000 km²

there you go, now you can measure area in rhode islands


25 lb. of mass converted to energy is about 1 Quad (1015 BTU)

this means that if america had a matter-antimatter reactor
and an unlimited supply of antimatter,
we would just need to choose one average size walrus
to sacrifice each year to meet our energy needs


gasoline has roughly the same energy content as Crisco
(~30,000 Calories per U.S. gallon)

they're both hydrocarbons so on some level this makes sense

importantly, this means that if you could digest gasoline,
just one cup a day would give you all the energy you need

it also means that if you could just eat Crisco
(which you can, don't let them tell you otherwise)
you'd only need to eat about a cup a day to hit 2,000 Calories

this also leads us to the related fact:


a typical gas pump dispenses energy at a rate of about 21 MW

most EV chargers on the other hand top out around 300 kW these days,
which is 70 times slower


a modern smartphone is about as powerful as a late '90s supercomputer

yes, if you took your iPhone 16 pro (~2 TFLOPS) back to 1999
you'd have the most powerful computer in the world
for about a year until ASCI white (~12 TFLOPS) comes along in 2000.

do you think they'd be disappointed with us?


falling down the stairs releases about as much energy as a gunshot
(~2,700 J)

if you weigh around 90 kg and use a deer rifle, that is


ringing a million doorbells at the same time
would be about as loud as a jet engine (120 dB)

i think this one is right assuming a doorbell ringing is 60 dB

the way i got to this one is by observing that
sound pressure from uncorrelated sources adds exponentially:
ten 60 dB sources add up to 70 dB
ten 70 dB sources add up to 80 dB
and so on

if you have a million doorbells try it and let me know how it goes