# How hard would you have to pull to split ONE atom? **URL:** \ **Category:** Factual Questions\ **Created:** [February 24, 2003, 8:54pm UTC](https://boards.straightdope.com/t/how-hard-would-you-have-to-pull-to-split-one-atom/157241 "2003-02-24T20:54:58Z")\ **Posts on this page:** 14\ **Page:** 1
**Author:** ![CC](https://avatars.discourse-cdn.com/v4/letter/c/f1d935/32.png) [@CC](https://boards.straightdope.com/u/CC)\ **Post date:** [February 24, 2003, 8:54pm UTC](https://boards.straightdope.com/t/how-hard-would-you-have-to-pull-to-split-one-atom/157241/1 "2003-02-24T20:54:58Z")
I realize to some extent how strong magnetism is compared to gravity. I know that two pieces of UNmagnetized iron would not jump together as a result of the gravity between them. How do these forces compare with the force that holds nuclei together? (I think that might be called either the weak or the strong force, or a combination) So, could someone pull a single atom apart? How about with a truck? I don’t have much facility with the math, and maybe I’m lost on the concept too? A little help? ---
**Author:** ![yme](https://avatars.discourse-cdn.com/v4/letter/y/35a633/32.png) [@yme](https://boards.straightdope.com/u/yme)\ **Post date:** [February 24, 2003, 9:01pm UTC](https://boards.straightdope.com/t/how-hard-would-you-have-to-pull-to-split-one-atom/157241/2 "2003-02-24T21:01:49Z")
I split atoms all the time by passing gas. ---
**Author:** ![GIGObuster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gigobuster/32/421_2.png) [@GIGObuster](https://boards.straightdope.com/u/GIGObuster)\ **Post date:** [February 24, 2003, 9:53pm UTC](https://boards.straightdope.com/t/how-hard-would-you-have-to-pull-to-split-one-atom/157241/3 "2003-02-24T21:53:43Z")
Take it with a grain of salt, but the Worst-case scenario people touched on this subject and oddly enough they also could not, like **yme** , leave fart jokes out of the picture. Great minds think alike 😉 : [http://www.genepool.addr.com/atom.html](http://www.genepool.addr.com/atom.html) > [@](#): > > 3: Splitting your atom Now that you’ve gotten a fair amount of U235, you’re going to have to find a way to split it. Don’t bother to try using a knife. This will not work. Not even the Ginsu knife. Instead, you are going to have to buy some neutrons. What you will need to do is propel a neutron into your U235 atom. Aim very carefully; you want to hit the middle, also known as the “nucleus.” There are many different methods you can try. Some choose to grab a handful of neutrons and just hurl them at the uranium. This may work, but it is very wasteful, and neutrons don’t just grow on trees. If you can find one, a neutron gun is an effective tool, but these are usually only available in some parts of the 23rd century. The two preferred techniques are A: finding a source that naturally emits neutrons, such as radium, and putting it in a glass tube with a small opening at one end or, B: using a straw-- put the neutrons in your mouth and fashion a “neutron spitball”, then blow through the straw toward the uranium. This is our recommended method, as it is much cheaper. (Note: do not confuse the two and put the radium in your mouth.) > > 4: Critical mass Once you have successfully split the atom, you will notice one very important thing: you didn’t blow up. The problem is that you only split one atom. This produces less energy than a cat having a gastric incident. Here is where critical mass comes in. We went with uranium not just because it’s bigger, but also because when it splits it gives off energy AND two neutrons. ---
**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\ **Post date:** [February 24, 2003, 10:05pm UTC](https://boards.straightdope.com/t/how-hard-would-you-have-to-pull-to-split-one-atom/157241/4 "2003-02-24T22:05:38Z")
Some good info: [http://www.fnal.gov/pub/inquiring/questions/strong\_force.html](http://www.fnal.gov/pub/inquiring/questions/strong_force.html) ---
**Author:** ![CC](https://avatars.discourse-cdn.com/v4/letter/c/f1d935/32.png) [@CC](https://boards.straightdope.com/u/CC)\ **Post date:** [February 24, 2003, 10:20pm UTC](https://boards.straightdope.com/t/how-hard-would-you-have-to-pull-to-split-one-atom/157241/5 "2003-02-24T22:20:55Z")
Ok, from the last site I gather that it would require about a million electronvolts to separate two protons. Can that be equated to any forces that we are acquainted with in daily life? I reiterate - could a couple of trucks develop enough force to do that? trains? battleships? ---
**Author:** ![handy](https://avatars.discourse-cdn.com/v4/letter/h/b5a626/32.png) [@handy](https://boards.straightdope.com/u/handy)\ **Post date:** [February 24, 2003, 10:32pm UTC](https://boards.straightdope.com/t/how-hard-would-you-have-to-pull-to-split-one-atom/157241/6 "2003-02-24T22:32:55Z")
“could a couple of trucks develop enough force to do that?” How would you attach both sides of the atom to each truck to pull? ---
**Author:** ![CC](https://avatars.discourse-cdn.com/v4/letter/c/f1d935/32.png) [@CC](https://boards.straightdope.com/u/CC)\ **Post date:** [February 24, 2003, 10:35pm UTC](https://boards.straightdope.com/t/how-hard-would-you-have-to-pull-to-split-one-atom/157241/7 "2003-02-24T22:35:57Z")
I hope you’re not serious. This is a theoretical question, right? ---
**Author:** ![Ring](https://avatars.discourse-cdn.com/v4/letter/r/6a8cbe/32.png) [@Ring](https://boards.straightdope.com/u/Ring)\ **Post date:** [February 24, 2003, 10:39pm UTC](https://boards.straightdope.com/t/how-hard-would-you-have-to-pull-to-split-one-atom/157241/8 "2003-02-24T22:39:37Z")
If the strong force had magnitude of 1 the electromagnetic force would have a magnitude of 1/137 and gravity would equal 6x10[sup]-39[/sup]. If you could somehow separate positive and negative charges, then two one-millimeter particles 30 meters apart would exert a force of three million tons on each other. The strong force is 137 greater than this, but only operates over very short distances. ---
**Author:** ![Happy\_Fun\_Ball](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/happy_fun_ball/32/17664_2.png) [@Happy\_Fun\_Ball](https://boards.straightdope.com/u/Happy_Fun_Ball)\ **Post date:** [February 24, 2003, 10:43pm UTC](https://boards.straightdope.com/t/how-hard-would-you-have-to-pull-to-split-one-atom/157241/9 "2003-02-24T22:43:34Z")
Electron volts are a measure of the energy in the nuclear bond. With a conversion rate of 1.602x10[sup]-19[/sup] Joule to 1 eV, you would not have to pull very hard to get the protons apart… To give you a better idea of the energy. 1 kW-hr = 3.60x10[sup]6[/sup] Joules. So 1 MeV = 2.25x10[sup]-20[/sup] kilowatt hours. Sounds easy, right? But how are you going to grab those protons smart guy? ---
**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\ **Post date:** [February 24, 2003, 10:46pm UTC](https://boards.straightdope.com/t/how-hard-would-you-have-to-pull-to-split-one-atom/157241/10 "2003-02-24T22:46:10Z")
> [@](#): > > \*Originally posted by CC \* > \*\*Ok, from the last site I gather that it would require about a million electronvolts to separate two protons. Can that be equated to any forces that we are acquainted with in daily life? I reiterate - could a couple of trucks develop enough force to do that? trains? battleships? \*\* The site uses the figure of 20-30 MeV binding the two protons in a Helium atom. Given that: 1 eV = 1.60217733 x 10[sup]-19[/sup] J and using 25 MeV for the binding energy, we get about 4 x 10[sup]-12[/sup] J to separate the protons in a helium atom. While this is a lot of energy on the atomic scale, it is trivially small macrocropically. Lifting an object that weighs one newton to a height of one meter requires one joule of energy. This is a trillionth of that. Hopefully, I did the calcs correctly… ---
**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\ **Post date:** [February 24, 2003, 11:14pm UTC](https://boards.straightdope.com/t/how-hard-would-you-have-to-pull-to-split-one-atom/157241/11 "2003-02-24T23:14:06Z")
> [@](#): > > \*Originally posted by Ring \* > \*\*If the strong force had magnitude of 1 the electromagnetic force would have a magnitude of 1/137 and gravity would equal 6x10[sup]-39[/sup]. > > If you could somehow separate positive and negative charges, then two one-millimeter particles 30 meters apart would exert a force of three million tons on each other. The strong force is 137 greater than this, but only operates over very short distances. \*\* What is the magnitude (in coulombs) of those charges you’re using there, **Ring**? BTW, I’ve often heard the comparisons stating that gravity is many orders of magnitude weaker than the electromagnetic force, and so on for the weak and strong nuclear forces. (The latter of which is but a residual force of the much stronger color force.) In any event, aren’t such comparisons akin to comparing apples and oranges? For example, comparing gravity and electromagnetism, one has to assume the masses for the particles in question for the former, and the charges for the particles in question for the latter. Masses and charges; apples and oranges. It makes perfect sense to compare the (attractive) force due to gravity between two protons to that of the (repulsive) force due to electromagnetism. The latter will be far stronger at any given separation distance. However, I had to assume a pair of particles. One will get a different answer if I had assumed two neutrons, or two uncharged baseballs. All that being said, when I taught this material, I used to bring in a bar magnet holding up a piece of steel. I would state that “this little magnet is overcoming the gravitational attraction of an entire planet.” This got the idea across of electromagnetism being orders of magnitude stronger than gravity, but again, the comparison always kind of bothered me. (I was comparing the gravitational attraction of two arbitrary masses to the magnetic attraction produced by a bar magnet of arbitrary strength.) Finally, I’m not going near range considerations for the nuclear forces… 🙂 ---
**Author:** ![Ring](https://avatars.discourse-cdn.com/v4/letter/r/6a8cbe/32.png) [@Ring](https://boards.straightdope.com/u/Ring)\ **Post date:** [February 25, 2003, 1:00am UTC](https://boards.straightdope.com/t/how-hard-would-you-have-to-pull-to-split-one-atom/157241/12 "2003-02-25T01:00:40Z")
> [@](#): > > \*Originally posted by robby \* > **What is the magnitude (in coulombs) of those charges you’re using there, Ring?** You’ll have to ask Richard Feynman the example is on page 2-4 volume 1 of his _“The Feynman Lectures on Physics.”_ > [@](#): > > In any event, aren’t such comparisons akin to comparing apples and oranges? > \*\* It depends. In Newtonian Mechanics Force just equals mass times accelertion. But when you start getting into GR or QM then the entire concept of force just sorts of fades away. ---
**Author:** ![Don\_Roberto](https://avatars.discourse-cdn.com/v4/letter/d/e47774/32.png) [@Don\_Roberto](https://boards.straightdope.com/u/Don_Roberto)\ **Post date:** [February 25, 2003, 1:37am UTC](https://boards.straightdope.com/t/how-hard-would-you-have-to-pull-to-split-one-atom/157241/13 "2003-02-25T01:37:43Z")
**Ring** ’s example (taken from Feynman) refers, in technical jargon, to the “coupling strengths” of the various forces. Thus the magnitudes of the charges, masses, nuclear strong force charges, would simply be the relevant quantities for two elementary particles (like a proton) which experience those interactions. Thus, if you compare the gravitational attraction between a proton and a proton and the Coulombic (electromagnetic) repulsion between a proton and a proton, you will find the EM force stronger by a factor of (1/137)/(6 x 10[sup]-39[/sup]). So you answer your query, **robby** , the apples-oranges problem isn’t really such a big deal. Ultimately, all these forces originate (and act upon) elementary particles; for these particles, the relatives strengths of the different forces are well defined. Since these elementary particles make up all the matter we see, if makes sense to talk about the relative strengths of these forces in terms of them. ---
**Author:** ![Don\_Roberto](https://avatars.discourse-cdn.com/v4/letter/d/e47774/32.png) [@Don\_Roberto](https://boards.straightdope.com/u/Don_Roberto)\ **Post date:** [February 25, 2003, 1:59am UTC](https://boards.straightdope.com/t/how-hard-would-you-have-to-pull-to-split-one-atom/157241/14 "2003-02-25T01:59:43Z")
To answer the OP: Well, to begin, no one really knows the functional form of the nuclear strong force, so your question can’t really be answered. However, here’s a calculation that is beyond heuristic: Consider the strong force to have a range of 1.2 fm (that’s a femto-meter), and let the force be constant over that range. The work done in separating two bodies is then Force x distance. The binding energy of a deuteron (one proton and one neutron) is about 2.2 MeV. Thus we have F = Work/distance = 2.2MeV/1.2fm ~ 2 MeV/fm ~ 160 J/m ~ 160Newtons ~ 35 lbs. I think you could probably manage that without the assistance of any trucks.