# The Naked Scientists Forum

### Author Topic: How big is a proton?  (Read 6329 times)

#### labview1958

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##### How big is a proton?
« on: 02/12/2009 02:09:33 »
We know the charge and mass of a proton. What is its volume?
« Last Edit: 06/12/2009 08:50:21 by chris »

#### Mr. Scientist

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##### Re: How big is a proton?
« Reply #1 on: 02/12/2009 02:10:51 »
We know the charge and mass of a proton. What is its volume?

It has a radius. You can look this up on wikipedia.

#### Mr. Scientist

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##### Re: How big is a proton?
« Reply #2 on: 02/12/2009 02:11:34 »
If you know mathematically the radius of something, you can estimate density and volume.

#### Pmb

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##### Re: How big is a proton?
« Reply #3 on: 02/12/2009 06:23:55 »
We know the charge and mass of a proton. What is its volume?
Since the proton is a composite particle it doens't have a well defined radius and therefore it doesm't have a well defined radius. The radius for the proton is chosen for a particular probability density.

#### labview1958

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##### Re: How big is a proton?
« Reply #4 on: 02/12/2009 06:37:47 »
From Wikipedia

Volume of a proton (~1.5×10−41 m³)

Is the volume of a neutron equals to a proton?

#### Soul Surfer

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• keep banging the rocks together
##### Re: How big is a proton?
« Reply #5 on: 02/12/2009 10:12:42 »
This question again is slightly more complex than it appears on first sight.  The volume of a proton (and neutron) as already pointed out is dependant of the strong force which limits how far the quarks can travel and how close you can pack protons and neutrons together before they interact.  Another measure is the "scattering cross section" which is used to measure how probable it is that particles will interact  this is measured by looking at the probability of particular particle collisions as beams of particles with known densities interact.  This can depend on the interaction energy of the collision and can be much smaller than the simple "size" quoted above because at very high energies it is the individual quarks that interact and not the whole proton.

#### labview1958

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##### Re: How big is a proton?
« Reply #6 on: 03/12/2009 06:13:59 »
Mass of proton :  1,6726 x 10^(-27) kg
Volume of a proton (~1.5×10−41 m³)

Density of proton = 1.12 x 10^17 kg/ m^3

Is it of any value in physics?

#### Mr. Scientist

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##### Re: How big is a proton?
« Reply #7 on: 03/12/2009 19:18:53 »
Mass of proton :  1,6726 x 10^(-27) kg
Volume of a proton (~1.5×10−41 m³)

Density of proton = 1.12 x 10^17 kg/ m^3

Is it of any value in physics?

Yes. It's called the Heirarchy Problem.

#### labview1958

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##### Re: How big is a proton?
« Reply #8 on: 04/12/2009 02:12:15 »
Quote
In the standard model, we have predictions that are based on why they have the mass they have, but the predictions soon manifest themselves into a strange paradoxical question: Why these certain masses, and not the other quantities? In quantum physics this is called the Heirarchy Problem

There are certain masses of particles, does it mean there are certain densities of particles?

#### Mr. Scientist

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##### Re: How big is a proton?
« Reply #9 on: 04/12/2009 09:54:45 »
Yes.

#### Mr. Scientist

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##### Re: How big is a proton?
« Reply #10 on: 04/12/2009 09:55:25 »
That's also a qoute from me isn't it? Where did you get it, here at this site?

#### labview1958

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##### Re: How big is a proton?
« Reply #11 on: 04/12/2009 13:31:10 »
Yes, from this site. Is a proton the densest particle?

#### Mr. Scientist

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##### Re: How big is a proton?
« Reply #12 on: 04/12/2009 15:13:38 »
Yes, from this site. Is a proton the densest particle?

Density relies on volume, so until the incongruity of zero-dimensional particles are solved, the answer is not so easy to deduct.

#### labview1958

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##### Re: How big is a proton?
« Reply #13 on: 06/12/2009 07:09:22 »
Can light pass through a proton?

#### syhprum

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##### Re: How big is a proton?
« Reply #14 on: 06/12/2009 08:44:14 »
No photons cannot pass thru but high energy particles interact with the internal Quarks rather than the whole Hadron.
Of course the wavelength of what we think of as light is vastly larger than a Proton and there is no interaction.

#### labview1958

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##### How big is a proton?
« Reply #15 on: 08/12/2009 06:07:26 »
Quote
The mass of the neutron is slightly higher than a proton, by approximately the mass of an electron.
Is it right to say mass of neutron = mass of proton + mass of electron

#### syhprum

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##### How big is a proton?
« Reply #16 on: 08/12/2009 09:10:06 »
No

When a Neutron decays into a Proton with the emission of an electron an anti neutrino is also emitted with some loss of mass due to the energy that this carries, hence the initial mass of the Neutron must be greater than the sum of a Proton plus an Electron.

#### labview1958

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##### How big is a proton?
« Reply #17 on: 14/12/2009 09:44:25 »
Is the mass of a neutron = mass of proton + mass of electron + mass of antineutrino ?

#### lightarrow

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##### How big is a proton?
« Reply #18 on: 14/12/2009 11:30:18 »
Is the mass of a neutron = mass of proton + mass of electron + mass of antineutrino ?
No, mass of a neutron = mass of proton + mass of electron + mass of antineutrino + energy released.

#### The Naked Scientists Forum

##### How big is a proton?
« Reply #18 on: 14/12/2009 11:30:18 »