Density of nuclear matter [urgent help needed]

Below is an extract from my Nuclear physics textbook,

"The relationship between the number of nucleons and their volume is very close to being proportional. This strongly suggests that the size and the spacing of the nucleons in an atomic nucleus is - as we had earlier assumed - hardly affected at all by the number of nucleons in the nucleus. It also means the the density of all atomic nuclei will be very similar and will, in fact, be be similar to the density of the individual nucleons themselves." (Pg 7)

As far as I am aware free nucleons have a greater mass than nucleons bound in a nucleus. So the density of a free nucleon should be higher than the density of a nucleus. Is this correct? Or does the radius of a free nucleon increase with its mass?

This question has come up several times on past papers but unfortunately I don't have the mark schemes.

Reply 1

elpaw

15

the mass of a free nucleon isnt bigger than a bound one, in fact, the (measured) mass off an (implied) bound nucleon should be greater than that of a free nucleon - e.g. if you measured the mass of a C-12 nucleus, it would be greater than that of 12 free nucleons.

Reply 2

DazYaYYY

Sang

Below is an extract from my Nuclear physics textbook,

"The relationship between the number of nucleons and their volume is very close to being proportional. This strongly suggests that the size and the spacing of the nucleons in an atomic nucleus is - as we had earlier assumed - hardly affected at all by the number of nucleons in the nucleus. It also means the the density of all atomic nuclei will be very similar and will, in fact, be be similar to the density of the individual nucleons themselves." (Pg 7)

As far as I am aware free nucleons have a greater mass than nucleons bound in a nucleus. So the density of a free nucleon should be higher than the density of a nucleus. Is this correct? Or does the radius of a free nucleon increase with its mass?

This question has come up several times on past papers but unfortunately I don't have the mark schemes.

what a stupid question, that will never come up but i'll explain it to you anyways, you shud be more worried about some of the other questions they will throw at u

ok the mass of all the constitudents split up is greater than when they are together ( BUT ONLY BY A SMALL AMOUNT )

the density in atomic nuclei is roughly the same ( YOU HAVE TO ACCEPT THAT ) , and you can check this using density = mass / volume where volume = 4/3 pi r3

well of course the radius increases with the size of the mass you fool, the more nucleons in the nucleus means A BIGGER MASS ANDDDDD hence the dimensions of the radius will increase due to the nucleons, that is why the density is the same pretty much for all nuclei

Reply 3

Turbonutter

Hm.

Nucleons don't have a specific volume, they're merely density functions. I doubt they're going to ask this question without just providing you some numbers and asking you to perform GCSE maths with them.

Density = mass/unit volume

Volume of a sphere = (4/3)*pi*r^3

Reply 4

Sang

OP

DazYaYYY

well of course the radius increases with the size of the mass you fool, the more nucleons in the nucleus means A BIGGER MASS ANDDDDD hence the dimensions of the radius will increase due to the nucleons, that is why the density is the same pretty much for all nuclei

For starters no need to get nasty. And here are 2 questions from a past papers.

1) Briefly discuss whether the volume of an oxygen nucleus is exactly 16 times as great as the volume of a hydrogen nucleus.. You may assume that the radius of a proton and neutron are the same. (JUN2003)

2) Suggest, with a reason, whether the density of the nucleus of Uranium-235 has approximately the same value as that in (i) (SPECIMEN PAPER)

*(i) Is the value worked out for the density of a hydrogen nucleus.

Reply 5

friday13th

I took the liberty of uploading some answers for you

jan 2003 and june 03

www.planetcarl.com/files

Density of nuclear matter [urgent help needed]

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