noun
speed per second; velocity per second
Used in physics, engineering, and news to express speed in units per second (e.g., meters per second). Often followed by a unit like メートル.
風の秒速は15メートルだった。
The wind speed was 15 meters per second.
このロケットの秒速は約8キロメートルです。
This rocket's velocity is about 8 kilometers per second.
noun
instant; moment; a few seconds
Colloquial use meaning a very short time, often in phrases like 秒速で (in a flash). Less common than the technical sense.
彼は秒速で宿題を終わらせた。
He finished his homework in a flash.
そのニュースは秒速で広まった。
The news spread in a matter of seconds.