Читать книгу Introduction to Desalination - Louis Theodore - Страница 36

The second is defined as the duration of 9,192,632,770 cycles of the radiation associated with a specified transition of the cesium-133 atom. It is realized by tuning an oscillator to the resonance frequency of cesium-133 atoms as they pass through a system of magnets and a resonant cavity into a detector. The number of periods or cycles per second is called frequency. The SI unit for frequency is the hertz (Hz). One hertz equals one cycle/s The SI unit for speed is the meter per second (m/s). The SI unit for acceleration is the meter per second per second (m/s²).