| 单词 | critical mass |
| 释义 | critical mass The minimum mass of fissile material that will sustain a nuclear chain reaction. For example, when a nucleus of uranium–235 disintegrates two or three neutrons are released in the process, each of which is capable of causing another nucleus to disintegrate, so creating a chain reaction. However, in a mass of U-235 less than the critical mass, too many neutrons escape from the surface of the material for the chain reaction to proceed. In the atom bomb, therefore, two or more subcritical masses have to be brought together to make a mass in excess of the critical mass before the bomb will explode |
| 随便看 |
物理辞典收录了3346条物理词条，基本涵盖了常用物理知识及物理英语单词词组的翻译及用法，是物理学习的有利工具。