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r.p.m. or gravity?

Cormac Shaw CSHAW at ollamh.ucd.ie
Thu Jan 29 06:06:40 EST 1998

On Wed, 28 Jan 1998, at 16:39:56 +0000 (GMT), 
Arturo Sanchez <asanchez at cibnor.mx> wrote:

>Can someone answer me the next question? How should I report the
>centrifugation speed r.p.m or gravity? Which one is correct? I have
>a discussion with a friend about this. I am reporting my methodology in
>r.p.m. but he says I should do it in g. I understand that r.p.m. are a
>unit of angular velocity equal to the uniform angular velocity of a body
>which rotates through an angle of 360  (2pi radians), so that every point
>in the body returns to its original point, in 1 minute. For me the key is
>in the "...uniform angular velocity". Am I right?

Nope. You definitely report 'g'. The r.p.m. value is only of use to 
someone with the exact same equipment. Reporting g allows anyone with 
a centrifuge to repeat the exiperiment (in theory anyway). As an 
aside, the guidelines for authors of The Biochemical Journal (if not 
others) recommends the term "rev./min" rather than "r.p.m." but thats 
just semantic waffle since you won't be using it anyway!



Cormac Shaw, BSc,                 |
Dept. of Industrial Microbiology, |  mailto:Cormac.Shaw at ucd.ie
University College Dublin,        |   phone: +353 (1) 706 1307
Dublin 4, Ireland                 |     fax: +353 (1) 706 1183
"Under the most rigorously controlled conditions of pressure,
temperature, volume, humidity, nutrients and other variables,
the organism will do as it pleases."

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