Day 273~366

Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min) is a measure of the frequency of rotation, specifically the number of rotations around a fixed axis in one minute. It is used as a measure of rotational speed of a mechanical component. In the French language, tr/mn (tours par minute) is the common abbreviation. The German language uses the abbreviation U/min or u/min (Umdrehungen pro Minute). A gramophone record (phonograph record in American English) or vinyl record, commonly known as a record, is an analogue sound storage medium in the form of a flat polyvinyl chloride(previously shellac) disc with an inscribed,…