首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
The History of the Atomic Bomb On August 2, 1939, just before the beginning of World War II, Albert Einstein wrote to then
The History of the Atomic Bomb On August 2, 1939, just before the beginning of World War II, Albert Einstein wrote to then
admin
2014-09-18
50
问题
The History of the Atomic Bomb
On August 2, 1939, just before the beginning of World War II, Albert Einstein wrote to then President Franklin D. Roosevelt. Einstein and several other scientists told Roosevelt of efforts in Nazi Germany to purify uranium-235, which could be used to build an atomic bomb. It was shortly thereafter that the United States Government began the serious undertaking known then only as "The Manhattan Project". Simply put, the Manhattan Project was committed to expediting research that would produce a viable atomic bomb.
The most complicated issue to be addressed in making of an atomic bomb was the production of ample amounts of "enriched" uranium to sustain a chain reaction. At the time, uranium-235 was very hard to extract. In fact, the ratio of conversion from uranium ore to uranium metal is 500:1. Compounding this, the one part of uranium that is finally refined from the ore is over 99% uranium-238, which is practically useless for an atomic bomb. To make the task even more difficult, the useful U-235 and nearly uselessU-238 are isotopes(同位素), nearly identical in their chemical makeup. No ordinary chemical extraction method could separate them; only mechanical methods could work.
A massive enrichment laboratory/plant was constructed at Oak Ridge, Tennessee. Harold C. Urey and his colleagues at Columbia University devised an extraction system that worked on the principle of gaseous diffusion, and Ernest O. Lawrence (inventor of the Cyclotron) at the University of California in Berkeley implemented a process involving magnetic separation of the two isotopes.
Next, a gas centrifuge was used to further separate the lighter U-235 from the heavier, non-fissionable U-238. Once all of these procedures had been completed, all that needed to be done was to put to the test the entire concept behind atomic fission ("splitting the atom", in layman’s terms).
Over the course of six years, from 1939 to 1945, more than $2 billion was spent during the history of the Manhattan Project. The formulas for refining uranium and putting together a working atomic bomb were created and seen to their logical ends by some of the greatest minds of our time. Chief among the people who unleashed the power of the atom was J. Robert Oppenheimer, who oversaw the project from conception to completion.
Finally, the day came when all at Los Alamos would find out if "The Gadget" (code-named as such during its development) was going to be the colossal dud of the century or perhaps an end to the war. It all came down to a fateful morning in midsummer, 1945.
According to the passage, if there were 500 tons of uranium ore, how many tons of useful uranium-235 could be extracted?
选项
A、1 kilogram.
B、10 kilogram.
C、50 kilogram.
D、500 kilogram.
答案
B
解析
按照短文的介绍,从铀的矿石提炼铀的比例是500比1然后再从这500分之一中提炼出有用的 235铀,只能是百分之一。所以,从500吨到一吨,再是百分之一,那就是10公斤235铀。
转载请注明原文地址:https://kaotiyun.com/show/LaTK777K
0
专业英语四级
相关试题推荐
Sincewearesocialbeings,thequalityofourlivesdependsinlargemeasureonourinterpersonalrelationships.Onestrengtho
Thegovernmentistobanpaymentstowitnessesbynewspapersseekingtobuyuppeopleinvolvedinprominentcases(1)______thet
Iamoneofthemanycitypeoplewhoarealwayssayingthatgiventhechoicewewouldprefertoliveinthecountryawayfromth
IwasinmythirdyearofteachingcreativewritingatRalphMcKeeVocationalSchoolinStatenIsland,NewYork,whenoneofmy
Thevenerable20-volumeOxfordEnglishDictionarycontainsabout700,000words,buttheeditorsrecentlyrealizedtheyweremiss
InafewweeksresearcherswillbeginscouringtheFloridaseafloorfora177-year-oldshipwreck—andtherestingplaceofdozens
InafewweeksresearcherswillbeginscouringtheFloridaseafloorfora177-year-oldshipwreck—andtherestingplaceofdozens
Marywaswatchingathrillingfilm,completely______totheoutsideworld.
Somanystudents______,theteacherthrewthetextbookinafitofanger.
Returningtomyapartment,______.
随机试题
案例:根据公司董事会制定的最新的发展战略,公司领导决定进行一次大规模的招聘,为公司的未来发展储备人才,尤其是计算机、市场营销等专业人才。人力资源部经理王希根据他与应聘人员短暂的几分钟面谈得出个人判断并以此来选聘应征者。在这个简短的会谈之前,王希的助手审查
主要以T-H蛋白和清蛋白为主构成的管型是
某矿山企业根据市场需要进行扩建。依据《建设项目安全设施“三同时”监督管理暂行办法》(国家安全生产监督管理总局令第36号),以该矿山企业的可行性研究报告为基础,对该扩建项目进行的安全评价是()。
干粉灭火系统调试在系统各组件安装完成后进行,下列属于系统调试内容的是()。
财产清查的目的是为了保证()与实存数一致。
从赎回角度看,在我国金融市场中下列()流动性最高。
下面哪一项是反映人体机能水平的指标?()
经济的市场化与政治的民主化是现代社会前进的两个车轮。但民主政治的发展不仅仅依托于民主体制的构建,还要立足于对民主体制在文化上的认同。无此,民主政治既会缺乏根源,又会出现操作失效的境况。因此,()。
在我国,人民代表大会上下级之间的关系是( )。
A、Theyaretoolatetooccupysomeoftheimportantmarkets.B、ThesellershavestolengoodsandsoldthemthrougheBay.C、Theb
最新回复
(
0
)