7 ms·

The way I remember Earth's approximate mass is the fact it's 10 times Avogadro's number in kg. My physics teacher always had a great way of drilling in these t

The way I remember Earth's approximate mass is the fact it's 10 times Avogadro's number in kg. My physics teacher always had a great way of drilling in these tidbits.

ThePowerOfFuet 4y ago
Gold.
deleted 4y ago
[deleted]
vitiral 4y ago
Take ten moles of earth, fire, wind and water. What do you have? Captain planet!
opwieurposiu 4y ago
Yes and the circumference of the earth is about 40 million meters. This is because a meter was originally supposed to be 1/10E6 the distance from the equator to the north pole through Paris.
- Someone 4y ago
  Nitpick: 1/10⁷, not 1/10⁶. They picked the power of ten that gave a reasonably-sized unit of length. They also made things complex by then picking a unit of mass that’s inconsistent with that: a gram isn’t the mass of 1m³ of water, but of 1/10⁶ m³ of water (a cubic meter is 10³ liters, and a liter of water weighs 10³ grams) Centimeter-gram-second (https://en.wikipedia.org/wiki/Centimetre–gram–second_system_of_units https://en.wikipedia.org/wiki/Centimetre–gram–second_system_...) really is superior in that sense (but of course, that’s relative to the arbitrary choice of using water to convert between mass and volume, and from that, length)
  - SJSque 4y ago
    10E6 = 10×10⁶ = 10⁷, so you can unpick that nit!
    - Someone 4y ago
      Yep!
  - naniwaduni 4y ago
    Picking 1/10^9 would also have had the advantage of making the distance from the pole to the equator ~1 gigacentimeter. Exploring a bit, picking 4 times that, as an estimate of the circumference, would give us a basic length unit of 4 cm (a pretty reasonable unit—bit over an inch and a half, fits right in with the variety of Chinese cun standards, for example). Then our immediate volume unit is 64 mL, which seems kind of small (on the scale of 2 floces), but ten of them make a decent "pint", so I think it can work—it's ~13% bigger than an imperial pint instead of ~12% smaller. the corresponding mass unit, at ~64 g, which again seems a bit small but manages to line up an average person's weight right around 1 kilo.
  - saalweachter 4y ago
    The gram is the easiest to save by working backwards from Avogadro's number. Avogadro's number is close to 24!, so we could redefine our mass unit as exactly 24! hydrogen atoms (or 4!!) and that comes out to within about 3% of a gram while being significantly easier to communicate to an extraterrestrial civilization.
- divbzero 4y ago
  Earth’s circumference around the poles is now given as 40,007.863 km [1]. So when the French Academy of Sciences defined the metre in the 1790s [2] the distance they measured from equator to North Pole was off by less than 2 km. [1]: https://en.wikipedia.org/wiki/Earth's_circumference https://en.wikipedia.org/wiki/Earth's_circumference [2]: https://en.wikipedia.org/wiki/Metre#Meridional_definition https://en.wikipedia.org/wiki/Metre#Meridional_definition
  - Normille 4y ago
    >o their 1793 measurement of the distance from the equator to the North Pole was off by less than 2 km.... Or, like a lot of people, the Earth's put on a bit of wieght in the intervening 200+ years
  - thrwaway298 4y ago
    I have read that the atronomers at the time actually knew that they were a bit off due to a mistake that was done by one of them. They spent several years making lots of smaller measurements that were added up. Each measurement was done twice to ensure correctness. One of the distances had two conflicting measurements, but due to a war, they could not return to make a third measurement and had to just choose one of them (the wrong one). They chose not to tell anyone because they feared politicians would use it to discredit the metric system.
deleted 4y ago
[deleted]
zem 4y ago
nice. filing it alongside the pi * 10^7 seconds in a year
mncharity 4y ago
> The way I remember Earth's approximate mass is For me, it's: Earth is a blue marble - in "Mega-view" (Mm zoomed to mm) - with a diameter of a baker's dozen Megameters. The volume of a ball is one half of its enclosing box, so that's ~(1E7)^3 or 1E21 m^3. Earth is rock (3 Mg/m^3) and iron (8 Mg/m^3) and averages 5 Mg/m^3. Or just bracket it - water,lead,gold is ~ 1,10,20 Mg/m^3). Giving an Earth mass of 5E24 kg. Actual value 6E24 kg. Brackets of water and lead give 1E24 to 11E24 kg. > a great way of drilling in these tidbits For me it's: Arm-sized, hand-sized, fingernail-sized, and "tiny"-sized, are 1000, 100, 10, and 1 mm. Zooming these by 1000^n gives scale-model "views". Mega-view with planet balls, kilo-view with cities in your palm, meter-view with buildings in hand, micro-view with red blood cell M&M's (yum), nano-view with virus balls (chewy shell, stringy inside), pico-view with H2O bumpy basketballs, femto-view with nuclei marbles. It's easier to remember how big things are, once they're toy-sized, and you've handled and played with them. Just something I crafted years back. Resulting videos didn't seem to user test well. I was set to dust it off, doing rapid iterative development over gorilla street usability testing... in Spring 2020. Ah well.

The way I remember Earth's approximate mass is the fact it's 10 times Avogadro's number in kg. My physics teacher always had a great way of drilling in these tidbits.

ThePowerOfFuet 4y ago

Gold.

deleted 4y ago

[deleted]

vitiral 4y ago

Take ten moles of earth, fire, wind and water. What do you have? Captain planet!

opwieurposiu 4y ago

Yes and the circumference of the earth is about 40 million meters. This is because a meter was originally supposed to be 1/10E6 the distance from the equator to the north pole through Paris.

Someone 4y ago
Nitpick: 1/10⁷, not 1/10⁶. They picked the power of ten that gave a reasonably-sized unit of length. They also made things complex by then picking a unit of mass that’s inconsistent with that: a gram isn’t the mass of 1m³ of water, but of 1/10⁶ m³ of water (a cubic meter is 10³ liters, and a liter of water weighs 10³ grams) Centimeter-gram-second (https://en.wikipedia.org/wiki/Centimetre–gram–second_system_of_units https://en.wikipedia.org/wiki/Centimetre–gram–second_system_...) really is superior in that sense (but of course, that’s relative to the arbitrary choice of using water to convert between mass and volume, and from that, length)
- SJSque 4y ago
  10E6 = 10×10⁶ = 10⁷, so you can unpick that nit!
  - Someone 4y ago
    Yep!
- naniwaduni 4y ago
  Picking 1/10^9 would also have had the advantage of making the distance from the pole to the equator ~1 gigacentimeter. Exploring a bit, picking 4 times that, as an estimate of the circumference, would give us a basic length unit of 4 cm (a pretty reasonable unit—bit over an inch and a half, fits right in with the variety of Chinese cun standards, for example). Then our immediate volume unit is 64 mL, which seems kind of small (on the scale of 2 floces), but ten of them make a decent "pint", so I think it can work—it's ~13% bigger than an imperial pint instead of ~12% smaller. the corresponding mass unit, at ~64 g, which again seems a bit small but manages to line up an average person's weight right around 1 kilo.
- saalweachter 4y ago
  The gram is the easiest to save by working backwards from Avogadro's number. Avogadro's number is close to 24!, so we could redefine our mass unit as exactly 24! hydrogen atoms (or 4!!) and that comes out to within about 3% of a gram while being significantly easier to communicate to an extraterrestrial civilization.
divbzero 4y ago
Earth’s circumference around the poles is now given as 40,007.863 km [1]. So when the French Academy of Sciences defined the metre in the 1790s [2] the distance they measured from equator to North Pole was off by less than 2 km. [1]: https://en.wikipedia.org/wiki/Earth's_circumference https://en.wikipedia.org/wiki/Earth's_circumference [2]: https://en.wikipedia.org/wiki/Metre#Meridional_definition https://en.wikipedia.org/wiki/Metre#Meridional_definition
- Normille 4y ago
  >o their 1793 measurement of the distance from the equator to the North Pole was off by less than 2 km.... Or, like a lot of people, the Earth's put on a bit of wieght in the intervening 200+ years
- thrwaway298 4y ago
  I have read that the atronomers at the time actually knew that they were a bit off due to a mistake that was done by one of them. They spent several years making lots of smaller measurements that were added up. Each measurement was done twice to ensure correctness. One of the distances had two conflicting measurements, but due to a war, they could not return to make a third measurement and had to just choose one of them (the wrong one). They chose not to tell anyone because they feared politicians would use it to discredit the metric system.

deleted 4y ago

[deleted]

zem 4y ago

nice. filing it alongside the pi * 10^7 seconds in a year

mncharity 4y ago

> The way I remember Earth's approximate mass is For me, it's: Earth is a blue marble - in "Mega-view" (Mm zoomed to mm) - with a diameter of a baker's dozen Megameters. The volume of a ball is one half of its enclosing box, so that's ~(1E7)^3 or 1E21 m^3. Earth is rock (3 Mg/m^3) and iron (8 Mg/m^3) and averages 5 Mg/m^3. Or just bracket it - water,lead,gold is ~ 1,10,20 Mg/m^3). Giving an Earth mass of 5E24 kg. Actual value 6E24 kg. Brackets of water and lead give 1E24 to 11E24 kg. > a great way of drilling in these tidbits For me it's: Arm-sized, hand-sized, fingernail-sized, and "tiny"-sized, are 1000, 100, 10, and 1 mm. Zooming these by 1000^n gives scale-model "views". Mega-view with planet balls, kilo-view with cities in your palm, meter-view with buildings in hand, micro-view with red blood cell M&M's (yum), nano-view with virus balls (chewy shell, stringy inside), pico-view with H2O bumpy basketballs, femto-view with nuclei marbles. It's easier to remember how big things are, once they're toy-sized, and you've handled and played with them. Just something I crafted years back. Resulting videos didn't seem to user test well. I was set to dust it off, doing rapid iterative development over gorilla street usability testing... in Spring 2020. Ah well.