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Text: エンジン回転数/電気モーター回転数

My understanding: Engine rpm/Electric motor rpm

My Issue: 回転数 has different meanings such as "rpm", "number of revolutions of
the engine", "Engine revolution speed", "engine speed". It will vary depending
upon the usage in any sentence. So, in sentences like above, Do we use rpm or
speed?
CC BY-SA 4.0
2020-10-29T11:55:15.287
82373
2020-10-29T22:44:34.307
32678
question
word-usage word-requests
The usage of 回転数 in a sentence
As you said, it will vary depending upon the usage in the context. In English,
_speed_ and _velocity_ are often used interchangeably, but [they are different
concepts](https://examples.yourdictionary.com/main-difference-between-speed-
and-velocity.html) in scientific contexts. Likewise, when 回転数 is used in
scientific or technological contexts, it usually refers specifically to either
rpm (1/60 s-1) or rps (s-1), depending on the field. The 回転数 of an engine is
usually measured in rpm. In many other contexts, however, thinking of 回転数 as
"rotation speed" or "number of revolutions" is enough, as the kanji suggest.
In mathematical contexts, 回転数 refers to [winding
number](https://en.wikipedia.org/wiki/Winding_number). The 回転数 of a restaurant
refers to seat turnover rate, or the number of customers per seat per day.
Either way, you should be able to tell from the context.

See also:

  * [Is there any difference between 速さand 速度?](https://japanese.stackexchange.com/q/65407/5010)
  * [回転速度 - Wikipedia](https://ja.wikipedia.org/wiki/%E5%9B%9E%E8%BB%A2%E9%80%9F%E5%BA%A6)
  * [回転数（数学） - Wikipedia](https://ja.wikipedia.org/wiki/%E5%9B%9E%E8%BB%A2%E6%95%B0_\(%E6%95%B0%E5%AD%A6\))
CC BY-SA 4.0
2020-10-29T21:59:45.340
82379
2020-10-29T22:44:34.307
2020-10-29T22:44:34.307
5010
5010
82373
answer