A small clarification

Posted by Mark Kelly (M) on December 19, 2005 at 03:02:49

In Reply to: a long answer trying to be as informative as possible posted by stark on December 18, 2005 at 18:23:12:

The resonant frequency in radians per second is given by ω = 1 / √C.m. if the compliance is stated in m/mN or cm/dyne and the mass is in grams. This is the basic law of simple harmonic motion.

Since there are 2 pi radians per second in one Hz, the equivalent is 1/2pi√C.m. Since compliance is always stated in μm/mN there is a factor of 10⁶ inside the square root sign, which is a factor of 10³ (1000) outside, so the formula is 1000 / 2√C.m. which is equivalent to your formula.

BTW differing values of lateral and vertical compliance give differing resonant frequencies in the vertical and horizontal planes. Since resonance is a dynamic phenomenon only dynamic compliance matters.

You can measure effective mass directly using a simple torsion pendulum - a small ruler, a peg and a stopwatch will suffice.

Mark Kelly

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Follow Ups Full Thread

Topic - High compliance -- low mass - OLLY 16:51:31 12/18/05 (13)

Re: High compliance -- low mass - HenryH 18:29:22 12/18/05 (0)

a long answer trying to be as informative as possible - stark 18:23:12 12/18/05 (10)

A small clarification - Mark Kelly 03:02:49 12/19/05 (5)

and an important clarification! - stark 08:30:34 12/19/05 (1)

Re: and an important clarification! - John Elison 13:07:05 12/19/05 (0)

Re: A small clarification - John Elison 07:15:17 12/19/05 (2)

Torsion pendulum - Mark Kelly 15:39:03 12/19/05 (1)

Thanks.... - John Elison 16:12:03 12/19/05 (0)

Re: a long answer trying to be as informative as possible - valvesonly 19:53:00 12/18/05 (1)

well... - stark 22:27:00 12/18/05 (0)

Re: a long answer trying to be as informative as possible - OLLY 18:56:27 12/18/05 (1)

all three are fine - stark 22:20:58 12/18/05 (0)

try www.vinylengine.com - tubesforever 17:02:27 12/18/05 (0)

Follow Ups

A small clarification - Mark Kelly 03:02:49 12/19/05 (5)

and an important clarification! - stark 08:30:34 12/19/05 (1)

Re: and an important clarification! - John Elison 13:07:05 12/19/05 (0)

Re: A small clarification - John Elison 07:15:17 12/19/05 (2)

Torsion pendulum - Mark Kelly 15:39:03 12/19/05 (1)

Thanks.... - John Elison 16:12:03 12/19/05 (0)

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