请输入您要查询的字词：

　

单词 second
释义
second
Physics

  • 1. Symbol s. The SI unit of time equal to the duration of 9 192 631 770 periods of the radiation corresponding to the transition between two hyperfine levels of the ground state of the caesium–133 atom.

    2. Symbol ″. A unit of angle equal to 1/3600 of a degree or 1/60 of a minute.

Astronomy

  • The fundamental unit of time in the SI system. It is defined as the duration of 9 192 631 770 cycles of the radiation from the transition between two hyperfine levels in the ground state of caesium-133. This definition is designed to produce 86 400 s in the mean solar day. See also Leap Second.

Chemical Engineering

  • 1. (Symbol s) A base SI unit of time equal to 1/60th of a minute and 1/3600th of an hour. Since May 2019, it is defined by taking the fixed numerical value of the unperturbed ground-state hyperfine transition frequency of the caesium-133 atom as 9 192 631 770 cycles of radiation.

    2. (Symbol ″) An angle equal to 1/60th of a minute or 1/3600th of a degree.

Biology

  • Symbol s. The SI unit of time equal to the duration of 9 192 631 770 periods of the radiation corresponding to the transition between two hyperfine levels of the ground state of the caesium–133 atom.
随便看

　

科学参考收录了60776条科技类词条，基本涵盖了常见科技类参考文献及英语词汇的翻译，是科学学习和研究的有利工具。

　

Copyright © 2000-2023 Sciref.net All Rights Reserved
京ICP备2021023879号 更新时间：2024/6/30 19:12:52