## Fermi Questions C

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### Re: Fermi Questions C

Name wrote:
Adi1008 wrote:How far does an air molecule (assume at STP) travel on average before it hits another air molecule, in meters?

Attempt

I believe that it would be $\frac{1}{n \sigma}$ , where $n$ is the number density and $\sigma$ is the cross sectional area of an air molecule (going to make the rough assumption that diatomic oxygen and nitrogen have relatively similar sizes).

$n$ is about $2.5 \times 10^{25} \mathrm{m^{-3}}$ (you can calculate this using the Ideal Gas Law if you don't have it memorized). The cross sectional area of diatomic oxygen or nitrogen is about $4 \times 10^{-19} \mathrm{m^2}$ .

Ok thanks! Also oops forgot to set up a question

Lets say you gained the ability to harvest salt from the ocean on a mass scale. If you take the salt and compacted it into a 1 meter radius sphere, what is it's escape velocity
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### Re: Fermi Questions C

Name wrote:
Name wrote:
Attempt

I believe that it would be $\frac{1}{n \sigma}$ , where $n$ is the number density and $\sigma$ is the cross sectional area of an air molecule (going to make the rough assumption that diatomic oxygen and nitrogen have relatively similar sizes).

$n$ is about $2.5 \times 10^{25} \mathrm{m^{-3}}$ (you can calculate this using the Ideal Gas Law if you don't have it memorized). The cross sectional area of diatomic oxygen or nitrogen is about $4 \times 10^{-19} \mathrm{m^2}$ .

Ok thanks! Also oops forgot to set up a question

Lets say you gained the ability to harvest salt from the ocean on a mass scale. If you take the salt and compacted it into a 1 meter radius sphere, what is it's escape velocity

My (very rough) attempt

How many complete rotations has the fastest pulsar made in the time between the extinction of the dinosaurs and the birth of Newton?
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whythelongface
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### Re: Fermi Questions C

Adi1008 wrote:How many complete rotations has the fastest pulsar made in the time between the extinction of the dinosaurs and the birth of Newton?

Attempt

RuBisCO is the most abundant enzyme in the entire biosphere. RuBisCO fixes carbon dioxide into ribulose bisphosphate, but can also fix diatomic oxygen into RuBP in a wasteful process known as photorespiration. How many kilograms of O2 are metabolized by RuBisCO within the entire biosphere in one second?
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### Re: Fermi Questions C

whythelongface wrote: RuBisCO is the most abundant enzyme in the entire biosphere. RuBisCO fixes carbon dioxide into ribulose bisphosphate, but can also fix diatomic oxygen into RuBP in a wasteful process known as photorespiration. How many kilograms of O2 are metabolized by RuBisCO within the entire biosphere in one second?

Can't find anything on the answer, and my answer seems off. Can you confirm what the answer is?

At the current rate this thread is moving at (starting from the first post) how many posts will there be in the time it takes for sound to travel from here to Sagittarius A*
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whythelongface
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### Re: Fermi Questions C

Name wrote:
whythelongface wrote: RuBisCO is the most abundant enzyme in the entire biosphere. RuBisCO fixes carbon dioxide into ribulose bisphosphate, but can also fix diatomic oxygen into RuBP in a wasteful process known as photorespiration. How many kilograms of O2 are metabolized by RuBisCO within the entire biosphere in one second?

Can't find anything on the answer, and my answer seems off. Can you confirm what the answer is?

I cannot confirm because I have not calculated it myself and am far too lazy to do so, but I'll give you some numbers:
"For every person on Earth, there are around five kilograms of RuBisCO in the biosphere."
"At ambient levels of carbon dioxide and oxygen, the ratio of the reactions is about 4 to 1, which results in a net carbon dioxide fixation of only 3.5."
I can't find the data for rate of carbon fixation, but if you really wanted to, you probably could.
WEST WINDSOR-PLAINSBORO HIGH SCHOOL SOUTH '18
EMORY UNIVERSITY '22
SONT 2017 5th Place Medalist [Microbe Mission]

"One little Sciolyer left all alone,
He went out and hanged himself and then there were none."

Congratulations to WW-P South for winning 14th place at Nationals!

Name
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### Re: Fermi Questions C

whythelongface wrote:
Name wrote:
whythelongface wrote: RuBisCO is the most abundant enzyme in the entire biosphere. RuBisCO fixes carbon dioxide into ribulose bisphosphate, but can also fix diatomic oxygen into RuBP in a wasteful process known as photorespiration. How many kilograms of O2 are metabolized by RuBisCO within the entire biosphere in one second?

Can't find anything on the answer, and my answer seems off. Can you confirm what the answer is?

I cannot confirm because I have not calculated it myself and am far too lazy to do so, but I'll give you some numbers:
"For every person on Earth, there are around five kilograms of RuBisCO in the biosphere."
"At ambient levels of carbon dioxide and oxygen, the ratio of the reactions is about 4 to 1, which results in a net carbon dioxide fixation of only 3.5."
I can't find the data for rate of carbon fixation, but if you really wanted to, you probably could.

I can't find the rate and really don't want to search more but the number is probably significantly higher then 2
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UTF-8 U+6211 U+662F
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### Re: Fermi Questions C

Well, might as well prep for next year.

How many leaves are in Manhattan?

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### Re: Fermi Questions C

UTF-8 U+6211 U+662F wrote:Well, might as well prep for next year.

How many leaves are in Manhattan?

Attempt

Name wrote:At the current rate this thread is moving at (starting from the first post) how many posts will there be in the time it takes for sound to travel from here to Sagittarius A*

By what magnitude is the electrostatic force of a eletron and proton greater then the gravitational force exerted from each other
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UTF-8 U+6211 U+662F
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### Re: Fermi Questions C

But sound can't travel in space

Attempt

How many full-scale models of the Titanic would you have to lay to build a bridge across the Atlantic Ocean (from around Maine to Spain)

edit: Or Unome can post his answer before I finish editing whoops
Last edited by UTF-8 U+6211 U+662F on May 1st, 2018, 12:36 pm, edited 2 times in total.

Unome
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### Re: Fermi Questions C

Name wrote:By what magnitude is the electrostatic force of a eletron and proton greater then the gravitational force exerted from each other

Attempt

Actual

How many electrons flow through an iPhone 8 over the course of one battery charge?
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UTF-8 U+6211 U+662F
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### Re: Fermi Questions C

Unome wrote:How many electrons flow through an iPhone 8 over the course of one battery charge?

Attempt

See my previous post for the next question

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### Re: Fermi Questions C

UTF-8 U+6211 U+662F wrote:How many full-scale models of the Titanic would you have to lay to build a bridge across the Atlantic Ocean (from around Maine to Spain)

Attempt

If a supernova occered and spewed out all it's energy in the form of visible light photons, how many photons will it spew out
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### Re: Fermi Questions C

Attempt

Edit: Dang it Name!
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### Re: Fermi Questions C

TheChiScientist wrote:
Attempt

Edit: Dang it Name!

Hey at least you got it right.
Quick advice, I feel like knowing numbers in SI units is easier, and convert when necessary. Using numbers in equations is usually SI units, and alotta conversations leaves more room for error.

Repost question:
If a supernova occered and spewed out all it's energy in the form of visible light photons, how many photons will it spew out
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### Re: Fermi Questions C

Attempt

How many times greater than the current value would the mass of the moon have to be in order to cause tides high enough to make Fort Collins, CO a coastal city at high tide? Assume uniform tides worldwide and ignore the effects of the increased mass on the oblateness of Earth.
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