Talk:Revolutions per minute
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[edit] Hertz in place of RPM?
Is there any reason to use rpm instead of Hertz in frequencies of the order of 1000 rpm? Wouldn't 17 Hz be more handy? Army1987 20:18, 20 April 2005 (virtual signature from edit history)
- We should probably consider that rotational motion was studied by mechanical engineers, while repetitive back-and-forth motions and vibrations were studied by electrical engineers and acoustical engineers. Large, early reciprocating steam engines revolved slowly, where an increase in speed from 65 to 70 RPM was not likely to be announced as "we have increased the top speed from 1.08333 Hertz to 1.16666 Hertz". I don't expect them to be receptive to a unit-of-measure change after hundreds of years. ~ Chris the speller 21:18, 15 November 2005 (UTC)
[edit] What exactly does RPM measure in an engine?
Hello. You say in your article that RPM measures the revolutions of an engine. What exactly is it measuring? An engine is stationary and does not move, but the pieces that make up an engine obviously do. So what piece of the engine is being measured? The crankshaft?
This is an encyclopaedia, so please be more specific. Dpolwarth 11:30, 3 August 2005
- Hi there. The RPM of an engine is measured before gears, so that would be directly from the crankshaft. This information should be included in the article, and as you can see above I've mentioned that it needs cleaning up. So I advise anyone taking on the task of cleaning up this article to add that information. --Badharlick 04:16, 14 November 2005 (UTC)
---could someone clarify exactly which cycle is measured in an engine? I mean, in a four-stroke engine, the physical shaft actually makes two complete rotations within each complete "cycle" of the engine. Which of these is measured by rpm?
[edit] This article is unclear, and needs cleaning up
I'm going to mark this article as requiring a cleanup, since it leaves more questions than it answers, and some that it just doesn't answer full stop. For instance, what is the standard radius of the rotating object from which the RPM is calculated?
Also the article is worded and formatted in a user unfriendly and inaccessable manner.
So changes to be made are: -add more information. -clarify current information. -rewrite/reformat the entire document for clarity.
--Badharlick 04:16, 14 November 2005 (UTC)
- The radius makes no difference when measuring RPM on a solid object. Imagine a 2-foot-diameter flywheel rotating at 200 RPM. A spot on the rim (radius 12 inches, which is half the diameter) goes around the axis 200 times every minute, and so does a spot that is at radius 6 inches (halfway from the axis to the rim), or any other spot. The spot on the rim, however, is traveling twice as fast (20.94 MPH) as the spot 6 inches out (10.47 MPH), because it has twice as far to go in each rotation. ~ Chris the speller 21:18, 15 November 2005 (UTC)
I have reworked the article. It seems considerably better and clearer to me, but that may not count for much. ~ Chris the speller 23:38, 15 November 2005 (UTC)
[edit] Notes reordered
I have reordered the notes above in chronological order (oldest at the top) and added virtual signatures and timestamps from the edit history page. ~ Chris the speller 21:18, 15 November 2005 (UTC)
[edit] Category
- Unit of velocity??? Ojw 10:33, 20 March 2006 (UTC)
