Fermi Questions C

[Raleway]

How many standard traditional light bulbs could fit inside the sun? (packing!)

[Unome]

Channeling my nonexistent packing knowledge (Click to Show Hidden Text)

- Earth radius is +E8 meters, solar radius is probably E10 meters, so volume of like E23
- Probably 100 lightbulbs per cubic meter, so E25
Fermi Answer: 25

True Answer (Click to Show Hidden Text)

- Off by quite a bit. The Sun's volume is 1.4E27, a lightbulb is around .0003 cubic meters. 4.67E30 is the answer.
True Answer: 30

How many carbon atoms are in an average 150-pound person?

[Ashernoel]

Channeling my nonexistent packing knowledge (Click to Show Hidden Text)

- Earth radius is +E8 meters, solar radius is probably E10 meters, so volume of like E23
- Probably 100 lightbulbs per cubic meter, so E25
Fermi Answer: 25

True Answer (Click to Show Hidden Text)

- Off by quite a bit. The Sun's volume is 1.4E27, a lightbulb is around .0003 cubic meters. 4.67E30 is the answer.
True Answer: 30

How many carbon atoms are in an average 150-pound person?

What I said (Click to Show Hidden Text)

hmmm so carbon atoms are probably like 20% of human so 20,000g and mass is 12g/mol so 3 moles and 23 per mol so 27?

What I should have said (Click to Show Hidden Text)

A 70 kg body would have approximately 7*1027 atoms. That is, 7 followed by 27 zeros:->Carbon 4.2*10e27 from random website yay

question: how many pacific oceans are needed to fill a school bus?

[Unome]

Channeling my nonexistent packing knowledge (Click to Show Hidden Text)

- Earth radius is +E8 meters, solar radius is probably E10 meters, so volume of like E23
- Probably 100 lightbulbs per cubic meter, so E25
Fermi Answer: 25

True Answer (Click to Show Hidden Text)

- Off by quite a bit. The Sun's volume is 1.4E27, a lightbulb is around .0003 cubic meters. 4.67E30 is the answer.
True Answer: 30

How many carbon atoms are in an average 150-pound person?

hmmm so carbon atoms are probably like 20% of human so 20,000g and mass is 12g/mol so 3 moles and 23 per mol so 27?

Btw 1) hide tag pls 2) post true answer 3) ask a question. It's not like there's any way for someone else to confirm with a correct answer since it's just looking stuff up and doing calculations.

[Ashernoel]

So I posted the question above, and here is another question for visibility!

question 1: how many pacific oceans are needed to fill a school bus?
Question 2: how many potatoes would i have to eat to get to Vega walking ?

[NeilMehta]

So I posted the question above, and here is another question for visibility!

question 1: how many pacific oceans are needed to fill a school bus?
Question 2: how many potatoes would i have to eat to get to Vega walking ?

I'm leaving the second one open for someone, but here's my answer for the first The pacific ocean has about E15 meters squared of water iirc (probably wrong)
A schoolbus can hold 2mx8mx2m of water, so E2
Would that be E-13??

[talkingturtle101]

Question 2: how many potatoes would i have to eat to get to Vega walking ?

My Answer (Click to Show Hidden Text)

- I don't know how far away Vega is, but i'll say it's 50 light-years away.
- A light year is around 10^13 km, or 10^16 meters, so Vega is 5*10^17 meters away.
- A potato could maybe give someone 100 calories.
- A normal person needs 2,000 calories and walks 15,000 steps. This is 0.12 calories per step, about.
- A step is about 1 meter.
- A potato could then give 750 steps.
- 5*10^17 divided by 7.5*10^2 rounds to a Fermi Answer of 15.

Kind of Close (Click to Show Hidden Text)

- Vega is 25 light-years away
- A light year is 10^16 meters, so Vega is 2.5*10^17 meters away.
- A normal potato is 163 calories.
- For every 20 steps, you burn 1 calorie, or 0.05 calories per step, so we assume you need 0.05 calories to take a step.
- A normal stride is 0.76 meters
- A potato could give you 3,260 steps.
- A potato could therefore give you 2477.6 meters
- 2.5e17 divided by this is almost exactly 10^14 potatoes, so Fermi Answer of 14.

Every fall, how many leaves are dropped by all trees across the U.S.?

[Unome]

Nice question (Click to Show Hidden Text)

- (Under)estimating E3 leaves dropped per tree per year
- Estimating E8 trees in the US (I (hope I) remember this from another problem about U.S. trees)
- So E11 leaves dropped
Fermi Answer: 11

True Answer (Click to Show Hidden Text)

- 2.28E10 trees in the U.S. There's probably a lot of deciduous trees, in the range of 1.5E10 from what I can figure out.
- There appears to be a little under E5 leaves on the average deciduous tree
So around E15
True Answer: 15

A part of the event that hasn't been covered yet in this thread (unless I'm remembering wrong):

How far away is the Earth from the sun, measured in units of blue whales laid end to end?

[Adi1008]

Nice question (Click to Show Hidden Text)

- (Under)estimating E3 leaves dropped per tree per year
- Estimating E8 trees in the US (I (hope I) remember this from another problem about U.S. trees)
- So E11 leaves dropped
Fermi Answer: 11

True Answer (Click to Show Hidden Text)

- 2.28E10 trees in the U.S. There's probably a lot of deciduous trees, in the range of 1.5E10 from what I can figure out.
- There appears to be a little under E5 leaves on the average deciduous tree
So around E15
True Answer: 15

A part of the event that hasn't been covered yet in this thread (unless I'm remembering wrong):

How far away is the Earth from the sun, measured in units of blue whales laid end to end?

My attempt (Click to Show Hidden Text)

The distance from the Earth to the Sun is 1.496E11 meters. Exponent of 11
Blue whales are ~30 meters. Exponent of 1
Dividing gives a Fermi Answer of 10

Actual Answer (Click to Show Hidden Text)

[url=https://www.wolframalpha.com/input/?i=(1+AU)%2F(length+of+a+blue+whale)]Wolfram Alpha[/url] gives an answer of 4.7E9 to 6E9

My question (sorry for not doing this the first time!) (Click to Show Hidden Text)

How many atoms are in the human body?

[Unome]

My Answer (Click to Show Hidden Text)

- Hydrogen is dominant (75%
mole fraction, 20% mass).
- Taking a 70 kg human, that's 1.4E4 grams of hydrogen, which is 1.4E4 moles.
- Using Avogadro's number, that's around E28 atoms.
Fermi Answer: 28

True Answer (Click to Show Hidden Text)

Google says 7E27.
True Answer: 28

How long would it take for the volume of the Pacific Ocean to flow through a standard kitchen sink?