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## #26 2012-01-27 12:28:26

anonimnystefy
Real Member
From: Harlan's World
Registered: 2011-05-23
Posts: 16,037

### Re: Fermi's questions!!!

hi

"Typical values are around 500ml..."

Here lies the reader who will never open this book. He is forever dead.
Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

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## #27 2012-01-27 14:49:28

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Fermi's questions!!!

Okay, I got that, thanks.

I have the answer by direct calculation, what do I do now?

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #28 2012-01-28 03:07:26

anonimnystefy
Real Member
From: Harlan's World
Registered: 2011-05-23
Posts: 16,037

### Re: Fermi's questions!!!

hi bobbym

Here lies the reader who will never open this book. He is forever dead.
Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

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## #29 2012-01-28 03:16:45

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Fermi's questions!!!

Hi;

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #30 2012-01-28 03:30:48

anonimnystefy
Real Member
From: Harlan's World
Registered: 2011-05-23
Posts: 16,037

### Re: Fermi's questions!!!

hi bobbym

if you used the usual formulas then it should be something like that.the point of these questions is not to get the exact right answer but rather to practice the use of formulas to get good estimates.e.g.:you'll notice that you can take oxygen to occupy 20%,21% or 22% but you will still get an approximately good answer.

next one:"how many pieces of popcorn would it take to fill up an average room?"

Here lies the reader who will never open this book. He is forever dead.
Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

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## #31 2012-01-28 03:42:26

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Fermi's questions!!!

That formula was created using all the estimates. The 6.0225 x 10^23 is Avogadro's number and it is obviously not precise. The 22.4 and 21% are also estimates.

Now, for the next question, I would say if anyone tried to fill up a room with popcorn I would immediately show up and eat it all.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #32 2012-01-28 03:54:06

anonimnystefy
Real Member
From: Harlan's World
Registered: 2011-05-23
Posts: 16,037

### Re: Fermi's questions!!!

well suppose we put you in an indestructible cage first.now,since you're trapped you can peacefully calculate the number.

if the previous argument fails,then my 2nd argument is that no one will actually fill the room.we are just wondering if we did then how many would we need.

Bonus question:"Would this amount of popcorn be enough to feed all the Chinese people?A human is fed if the food given to him satisfies his hunger for at least two hours"

Last edited by anonimnystefy (2012-01-28 03:54:33)

Here lies the reader who will never open this book. He is forever dead.
Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

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## #33 2012-01-28 04:12:24

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Fermi's questions!!!

Define an average size room? In your country it would be totally different than say England or Japan or the US.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #34 2012-01-28 04:18:43

anonimnystefy
Real Member
From: Harlan's World
Registered: 2011-05-23
Posts: 16,037

### Re: Fermi's questions!!!

well,let it be a room of size 4 by 4 by 2.

Here lies the reader who will never open this book. He is forever dead.
Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

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## #35 2012-01-28 04:26:41

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Fermi's questions!!!

Meters, I presume?

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #36 2012-01-28 04:29:04

anonimnystefy
Real Member
From: Harlan's World
Registered: 2011-05-23
Posts: 16,037

### Re: Fermi's questions!!!

yup.i don't know how to use yards and such stuff.

Here lies the reader who will never open this book. He is forever dead.
Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

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## #37 2012-01-28 05:22:44

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Fermi's questions!!!

Okay, I will begin working on it.

Cooking up a bag of popcorn of the movie theatre variety, I then proceeded to measure a few and take the average. My best estimate is that one popcorn has an equivalent volume to a 3 / 4 inch diameter sphere.

So 825 000 popcorn would fit in the room.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #38 2012-01-28 09:08:28

anonimnystefy
Real Member
From: Harlan's World
Registered: 2011-05-23
Posts: 16,037

### Re: Fermi's questions!!!

hi bobbym

nice work.

btw,i really don't like that you edit posts like that instead of posting new post.sometimes i can think that you haven't answered and just miss your edited post.

Here lies the reader who will never open this book. He is forever dead.
Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

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## #39 2012-01-28 09:23:32

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Fermi's questions!!!

Hi;

On many forums double posting is not allowed. It is not a habit I would like to develope.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #40 2012-01-28 09:42:25

anonimnystefy
Real Member
From: Harlan's World
Registered: 2011-05-23
Posts: 16,037

### Re: Fermi's questions!!!

then you shouldn't have posted the pre-edited post.anyway this forum doesn't have that rule!

Here lies the reader who will never open this book. He is forever dead.
Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

Offline

## #41 2012-01-28 10:08:53

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Fermi's questions!!!

The first post ws to let you know I was working on it. How do you know this forum does not have that rule?

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #42 2012-01-28 10:12:13

anonimnystefy
Real Member
From: Harlan's World
Registered: 2011-05-23
Posts: 16,037

### Re: Fermi's questions!!!

well why would i need that information if it will keep me from seeing your latest post.

and for the rules:Forum Rules

Here lies the reader who will never open this book. He is forever dead.
Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

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## #43 2012-01-28 10:17:09

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Fermi's questions!!!

Yes, those are some of the rules. But as I said, I consider it poor form. Sort of like muttering to yourself in the street.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #44 2012-01-28 10:28:47

anonimnystefy
Real Member
From: Harlan's World
Registered: 2011-05-23
Posts: 16,037

### Re: Fermi's questions!!!

still those are the rules.

next Q:"Some men and women are attracted to each other because of love,but all men and women are attracted to each other because of the force of gravity.What is the gravitational force between an average man and an average woman talking to each other?"

Last edited by anonimnystefy (2012-01-28 10:29:04)

Here lies the reader who will never open this book. He is forever dead.
Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

Offline

## #45 2012-01-28 10:42:23

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Fermi's questions!!!

I find it more distracting and difficult to follow when someone is double or triple posting at me, that is when I miss posts completely.

With all due respect to Enrico, when a question has a formula for the answer as this one does there is not much estimation involved. In this case a big, bad element of uncertainty has been added. I can estimate the mass of the average female and male but how do I estimate the average distance???

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #46 2012-01-28 10:46:39

anonimnystefy
Real Member
From: Harlan's World
Registered: 2011-05-23
Posts: 16,037

### Re: Fermi's questions!!!

well they are talking to each other.

Here lies the reader who will never open this book. He is forever dead.
Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

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## #47 2012-01-28 10:49:45

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Fermi's questions!!!

On the telephone?

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #48 2012-01-28 11:01:25

anonimnystefy
Real Member
From: Harlan's World
Registered: 2011-05-23
Posts: 16,037

### Re: Fermi's questions!!!

no,in person.take that they are standing 2 (60 cm) feet from each other.

Here lies the reader who will never open this book. He is forever dead.
Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

Offline

## #49 2012-01-28 16:20:54

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Fermi's questions!!!

Hi;

We use Newtons law of universal gravitation.

Using the tables provided by wikipedia tha average male weight had to estimated at 78.6 kg . The average female weight as 66.2 kg. Now you just plug in to the formula:

So the gravitational attraction between the two is 9.64 x 10^(-7) newtons.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #50 2012-01-29 01:33:21

anonimnystefy
Real Member
From: Harlan's World
Registered: 2011-05-23
Posts: 16,037

### Re: Fermi's questions!!!

hi bobbym

nice work!

Q:"if an atom of hydrogen was blown up do that the nucleus was the size of a baseball,then what would be the distance between the nucleus and the electron circling it at that size?"

Here lies the reader who will never open this book. He is forever dead.
Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

Offline