Talk:Revolutions per minute

Hertz in place of RP?

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)

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?

Rotation —Preceding unsigned comment added by 69.125.110.223 (talk) 20:23, 4 April 2008 (UTC)

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)

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)

Category

• Unit of velocity??? Ojw 10:33, 20 March 2006 (UTC)

N1

The article N1 redirects here, but that's not mentioned here. 85.179.21.26 13:19, 2 September 2007 (UTC)

How do you measure rpms?

What devices are used to measure rpms... this should be in the main article too. —Preceding unsigned comment added by 216.73.235.7 (talk) 21:22, 11 July 2008 (UTC)

rpm

what if i use the word rotations instead of revolutions? —Preceding unsigned comment added by Cbhan (talk • contribs) 14:35, 26 January 2009 (UTC)

"RPM" or "rpm" ?

In an official plate declaring nominal rating of an electrical engine, should I write "RPM" or "rpm" ? (I'm adding USA units to a "SI" plate) Thanks Michele. —Preceding unsigned comment added by 84.220.225.212 (talk) 22:08, 27 February 2010 (UTC)

This talk page is not the right place for your query. Ask your question at the reference desk. Graham87 08:16, 28 February 2010 (UTC)

Revolve v. Rotate

In many cases, Revolve and Rotate have different meanings. In this article, the two words are used interchangeably. AaronzAccount (talk) 22:05, 28 June 2011 (UTC)

The revolution as a measure of angle

I am of the firm conviction that the turn or revolution is the most natural measure of angle and unfortunately one of the most neglected. To children we explain that a circle is made up of 360 degress. However the circle itself exists and each rotation around its centre, which is of an angle of 360 degrees or 2pi radians results in being at the same position.

It therefore follows that rpm is a measure of angular velocity. This interpretation is consistent with the examples given on this talk page. To convert to radians per second, multiply by 2pi radians/revolution and 1 minute/60 seconds. Tony.wallace.nz (talk) 07:03, 22 February 2012 (UTC)

Revised

Hi all.

As per my earlier post I have rewritten this article emphasising rpm as a measure of angular velocity. Frequency and angular velocity being related by the number of complete revolutions within a time period being the frequency: thus f=2πω. I believe this angular velocity approach to be consistent with common usage.

Tony.wallace.nz (talk) 08:20, 22 February 2012 (UTC)

I don't know anything about this subject, and I only have this article on my watchlist in case of vandalism, but this rewrite sounds good to me. Graham87 15:06, 22 February 2012 (UTC)

I don't know what you mean, but your saying that f=2πω is completely and totally wrong and incorrect

The correct formula is ω = 2πf just google it. it is high-school stuff. — Preceding unsigned comment added by 104.129.194.79 (talk) 15:03, 23 April 2015 (UTC)

Move discussion in progress

There is a move discussion in progress on Talk:Kilometres per hour which affects this page. Please participate on that page and not in this talk page section. Thank you. —RMCD bot 01:00, 10 December 2013 (UTC)

Move discussion in progress

There is a move discussion in progress on Talk:RPM (disambiguation) which affects this page. Please participate on that page and not in this talk page section. Thank you. —RMCD bot 21:47, 2 May 2017 (UTC)