Hiroshima B0mb had Uranium, Nagasaki B0mb had Plutonium.. Why?

Please excuse my ignorance, but I have a few questions regarding WW2, some anecdotal "laws of science", and history/the future in general:

1. If matter cannot be created nor destroyed, then what happened to the 2 uranium atoms that came together and converted into "energy" when the US dropped the atomic b0mb ("Little Boy") on Hiroshima?

2. Why did the US use a plutonium bomb ("Fat Man") on Nagasaki? Why not just use the same types of b0mbs for each attack?

3. What other historical events would you consider comparable to the dropping of the atomic bomb (if any)?

4. Do you think we will see use of nuclear weapons in warfare during your lifetime?

for your first question; the laws of thermodynamics were changed to mass and energy cannot be created or destroyed but they can convert between the two. This only works for when fusion or fission occur. And yes the equation proposed by Einstein is used to calculate the amount of energy that is created when matter is reduced. That equation is E(nergy)=M(ass)C(acceleration)squared.

Just letting you know.

I also remember that during WW2 it was hard to purify radioactive elements and obtain sufficient mass of the right isotopes. Thus, it was easier to obtain Uranium but Plutonium was more conductive for creating a fission reaction.

Just what I remember.

a reply to: FamCore

You could probably just read about it here:

Science Behind the Atom Bomb

That's probably a pretty good source.

The isotopes uranium-235 and plutonium-239 were selected by the atomic scientists because they readily undergo fission. Fission occurs when a neutron strikes the nucleus of either isotope, splitting the nucleus into fragments and releasing a tremendous amount of energy. The fission process becomes self-sustaining as neutrons produced by the splitting of atom strike nearby nuclei and produce more fission. This is known as a chain reaction and is what causes an atomic explosion.

When a uranium-235 atom absorbs a neutron and fissions into two new atoms, it releases three new neutrons and some binding energy. Two neutrons do not continue the reaction because they are lost or absorbed by a uranium-238 atom. However, one neutron does collide with an atom of uranium-235, which then fissions and releases two neutrons and some binding energy. Both of those neutrons collide with uranium-235 atoms, each of which fission and release between one and three neutrons, and so on. This causes a nuclear chain reaction.

a reply to: FamCore

1) Matter can be created and destroyed (it's energy that you're thinking of. It can't be created or destroyed, just changed from one form to another).

2) They used two different types of materials because they had two different types of detonation systems. On used a concussive shot, the other implosion. They most likely did it to see which one (if any) did better in the field.

3) Depends upon what you mean by "comparable" - death and destruction? or historical significance?

4) Not unless it's a terrorist attack or rogue state. For many decades most leaders of nations with nuclear weapons know that it's really not an option because the detonation of the weapons do not just affect that local area, but can have a global impact on neutral or even friendly allies.

a reply to: eriktheawful

Thanks for your response - clarification for what I mean by "comparable" to the dropping of the atomic bomb, I'm wondering what other destructive, geopolitical events seem to compare in terms of their impact on the world and the history books

They weren't sure the plutonium device would work, kind of a test I suppose. They knew of course the uranium device(simpler) would work.

1) Matter can be created and destroyed (it's energy that you're thinking of. It can't be created or destroyed, just changed from one form to another).

Matter can be changed into energy , yet never totally destroyed. The closest would be in a black hole with a near infinite gravitational force that theoretically destroys mass down to information.
Energy is created from matter , yet the total amount of matter cannot be transformed into energy.

In fact , the total mass of the universe that was there at the Great Expansion still remains today in different forms.

Again , "matter cannot be created nor destroyed"
The First Law of Thermodynamics.

They were experimental.Tests. At the time , some research scientists believed that the first would destroy the world. So , they had 2 experimental versions...different , yet the same.
Playing with fire and hedging the bet as the old sayings go..

They could not produce enough uranium for the first bomb, so they used plutonium for the second one. It was an experiment.

This also gave the opportunity to measure the different substances on the area affected.

Remember both bombs were detonated over civilian areas, today you would probably call it mass genocide.

There were plans to detonate them in the sea for the Japanese officials to watch, but this plan was abandoned due to fear the bomb would fail.

a reply to: FamCore

Could it possibly because they didn't have enough fissionable material, and had to borrow some from the Germans heavy water project, when they overran the sites after the armistice.

a reply to: Gothmog

Like I said previously. The Law of Thermodynamics was change to include nuclear reactions. Thus, the combination of matter and energy is conserved but they can convert between the two using Einstein's E=MC(squared). Until Meitner reviewed her former partner Hahn's experimental work; there had never been a situation where mass had been converted to energy. Hahn had thought his experiment had been contaminated originally. Meitner and her nephew were the ones to show that Hahn's experiment had followed according to Einstein's proposal of E=MC^2.

As long as you are not dealing with nuclear fission or fusion, then the original laws of Thermodynamics hold true. You cannot create or lose mass. You also can not create or lose energy. Only during nuclear reactions can mass be lost and energy created.

I wouldn't be overly concerned about those two bombs

Its the next one you need two worry about

originally posted by: feldercarb
a reply to: Gothmog

Like I said previously. The Law of Thermodynamics was change to include nuclear reactions. Thus, the combination of matter and energy is conserved but they can convert between the two using Einstein's E=MC(squared). Until Meitner reviewed her former partner Hahn's experimental work; there had never been a situation where mass had been converted to energy. Hahn had thought his experiment had been contaminated originally. Meitner and her nephew were the ones to show that Hahn's experiment had followed according to Einstein's proposal of E=MC^2.

As long as you are not dealing with nuclear fission or fusion, then the original laws of Thermodynamics hold true. You cannot create or lose mass. You also can not create or lose energy. Only during nuclear reactions can mass be lost and energy created.

Nothing changed except the belief a nuclear explosion would be able to convert 100% .They were now able to include factual information on nuclear fusion . BTW , which led to a better understanding of how stars work
No , no matter how much is tried , you cannot create nor destroy mass (matter) . Not even the energy of a supernova burst can do that. Neither can the total collapse under near infinite gravitational force that follows.
Where in the world do folks get their science information ?
Please dont say on Social Media....
With that being said , there is the Theory of Matter/Anti-Matter interaction . Theoretically that may be able to convert 100% of mass to energy. Nothing else can even come close

1. The Little Boy nuclear device was a "gun" type weapon. A pit of U235 was shot by a high explosive into a receptor U235 creating an almost instantaneous critical mass and chain reaction. With so many tests at Alamogordo with Uranium devices, there was practically no doubt a Uranium device wouldn't work. Theoretical tests, however, one detonation almost occurred during "bullet and "target" design. The resulting chain reaction of the Little Boy device over Hiroshima created about 17 kilotons equivalent of TNT. Detonated at 1800 feet above ground level, leveled just about everything in a 1 mile radius. The bomb, casing, electronics and especially the uranium was instantly vaporized at detonation and the resulting Alpha, Beta, and Gamma plus the rapid heat expansion caused fires and instant death for 2.5 miles from ground zero. Fires were started up to 5 miles away.

2. Plutonium Bombs were not as understood as uranium bombs. In fact, the Trinity Site first test of a nuclear device was a plutonium bomb. Trinity Test Plutonium devices were the implosion type which means that explosives all around the 6 inch sphere had to explode at the precise same microsecond with almost the exact same force. I'm not sure if the Trinity and the Nagasaki bombs were the same model, but the Trinity device exploded with about 22 kilotons of TNT equivalence. Fat Man Device

3. Between 1945 and up until the late '80s we had nuclear detonation testing, above ground until the '70s and below ground until the late '80s (some say '90s IDK) There was only one that really got everyone's attention and that one was the Tsar Bomba, an almost 60 megaton device that was exploded by the Soviet Union over an Arctic island. Tsar Bomba

4. (sigh) God, I hope not. I have read people on here saying so flippantly, "Let's drop a nuke on them!" I'm guessing these are people who have never seen what just conventional bombs can do. They have never been standing over 5 miles away from a nuclear blast and been knocked down by the hot air blast. smfh

If your brain and eyes could process this fast,

this is what is the last thing they'd see.







I can think of worse ways to go.

originally posted by: Gothmog

Where in the world do folks get their science information ?
Please dont say on Social Media....

How about classes in Chemical Engineering.

a reply to: FamCore

From my vague memory the Americans were researching Uranium bombs and the Germans were researching Plutonium bombs, or possibly the other way around. Once America possessed the German tech they switched elements. It's not Gospel but I do remember watching it albeit many years ago. A city's inhabitants vaporised in mere seconds. Ain't war fun?

originally posted by: vonclod
They weren't sure the plutonium device would work, kind of a test I suppose. They knew of course the uranium device(simpler) would work.

I messed up my history, they tested the plutonium device(Trinity..implosion type) first because it was unknown if it would work properly, they did not bother testing the uranium(gun type) because they knew it would work.

My understanding is that, in those early days of uranium refining, the Manhattan Project had only amassed enough material for a single uranium bomb and that one was used on Hiroshima. Plutonium was quicker to refine but much more difficult to achieve critical mass for an explosion, requiring compression by conventional high explosives surrounding a sphere of plutonium.

Trinity was the proof of concept for the plutonium bomb and the 2nd of that type was used on Nagasaki.

a reply to: FamCore

2. Why did the US use a plutonium bomb ("Fat Man") on Nagasaki? Why not just use the same types of b0mbs for each attack?

to see which one kills the most people but destroys the least property
to see which one destroys the most property and kills the most people
to see which one causes the most horrific injures and what sort each inflicts
to see if both types work

to close off a hyper dimensional portal according to one article I read.