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what is the formula for mass


Colin

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In physics, the mass of an object is determined by dividing its weight by its acceleration due to gravity...ideally in a vacuum. Maybe you are talking about units of work/energy, such as foot-pounds? A foot-pound is what it takes to move a mass weighing one pound a distance of one foot at the acceleration rate of one foot per second, per second. Or maybe you are looking for pounds per cubic foot? That is found by dividing the cubic feet of an object, by its weight. Or maybe you are looking for specific gravity of an object? That is the RATIO of the weight of a given volume of an object to that same given volume of a standard...the standard used for solids and liquids is that of water...and for gases is that of either air or hydrogen. Hope this has helped some.

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The question is difficult to understand.

Let me take a shot in the dark and conclude that you're trying to calculate the weight of a speaker box based on the dimensions of plywood or MDF out of which you construct it. ("This is nonsense up with which we will not put.")

First you figure the volume of the board. That is width x length x thickness. If those are in inches, the resulting number is volume in cubic inches. That is sometimes expressed as inches raised to the the power of 3, with the three being a small superscript. Or in^3

Then you have to know the density of the wood. I can find that for you tomorrow in a handbook. Density can be expressed in pounds per cubic inch. Or LBS/in^3.

If you multiply Area (in^3) times density (LBS / in^3) you get LBS.

If you can explain the problem you're facing, I'll be glad to help.

Gil

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Right on, Gil! A few clues as to the problem to be solved would help.

Then again HDRBbuilder's first answer may resolve the problem if it is a Bose. Just weigh the problem and then shove it off a cliff... have your neighborhood speed cop hit it with his radar... that gives you a high tech answer and, hopefully, enough kindling to spend a cozy evening listening to an Acoustimass snap, crackle and pop in the fireplace at its highest potential fidelity! 11.gif -HornED

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man, physics revisited. i still can't relate to that, in a vacuum, a feather has the same acceleration as a brick. i think that vacuum thing is the key. so iow, acceleration is just a gravitational pull constant. here on earth that's 9.8m/sec squared or 32 ft/sec squared.

how did i do? 9.gif

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yeah, Boa...but the vacuum is a necessity...because, without the vacuum, an object will reach a terminal velocity based on its wind resistance...kinda like a skydiver in a stabile body position...terminal velocity is around 120 MPH...but in a delta "tracking" position, that terminal velocity increases to around 180+ MPH!!..because, even though you are actually falling at the same velocity DOWNWARD along the vertical side of a right triangle, you are now travelling along its hypotenuse, at that same downward rate!! Been there, done that..."Oh, my misspent youth!!" Sure was FUN though!! 9.gif

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if you take height times weight times length times width in inches and in pounds, you answer is what? footpounds? cubic feet? what?

Height...In linear dimensions Mulitiplied by

Length...In linear dimesions....Mulitiplied by

Width...In Linear dimension

Gives you a cubic volume in the scale you selected...cubic inches..meters..cathairs...what ever...

Taking a cubic volume and multiplying by weight will only give you a value that is meaningful to UPS, FED-EX, etc.

A footpound is the measure of a Work(force)...not a static entity. If I recall correctly it has somethind to do with neutered meters....

6.gif6.gif

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Puts me in mind of an old formula about: "The heat of the ......."

Ow - Ouch - Dang It Woman - I was only having a li'll fun ! Fine go to bed then !!

'Sides I was referring to:

The heat of the radiator is directly proportional to the pressure on the accelerator !

She must be some sorta prevert 'cause I can't imagine any sexist/chauvinist poem That start thet way !

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the question and some of the response makes no sense.

bodies attract, the mass of a body determines the extent of attraction (i.e. the strength of the gravitational field). The larger the mass, the greater the attraction (gravity). Any massive object will experience the influence of a gravatational field and will affect other massive bodies. It has nothing to do with "terminal velocity" or "vacuum".

Conceptually mass is the "absence of void". Displaced void generates gravity.

It wasn't my idea.

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Thats for all the replies, but I am seeking nothing so fancy as what you suggest. The weight of a loudspeaker seems to make a big difference in the sound, usually because of the dampening effect of the construction. I am trying to get an idea of the mass of a loudspeaker, compared to other loudspeakers, in order to have a rough idea of something other than mere size.

For example, Coincidents simply cherry bookshelf Triumph Signatures are quite similar in appearance to Axiom Audios M3Tis (http://www.enjoythemusic.com/magazine/archives/). They both share the same size and number of drivers, a truncated rectangular shape, Canadian origin, cherry finish and approximate size. They could be cousins, yet they could not sound and cost more different. In comparison to the slick Triumph Signatures urbanites, the M3Tis are country bumpkins. They are only ¼ of Triumph Signatures price and yet sound punchy, exuberant, joyous, bright and surprisingly deep. The Triumph Signatures however, are some of the most neutral, level, even toned bookshelves loudspeakers that I have had the pleasure to audition. They have more in common with the reserved Vince Christian E6C satellites (http://www.enjoythemusic.com/magazine/equipment/0702/vincechristiane6c.htm) than any other loudspeaker I have auditioned so far. In addition to numerous other quality details, the Triumph Signatures are also veneered inside and out, plus they weigh twice of the M3Tis.

Or compare these two to the Classic Audio Cinema Ensemble horns. These are about the same price as the Triumph Signatures, but a larger box, with a big rectangular midrange horn (also in Cherry). Yet, the Cinema Ensembles are much lighter weight than the Triumph Signatures.

So in addition to getting an idea of the volume of a loudspeaker, I want to include the weight. Combining the weight and the dimensions gives you an idea of the actual mass of a loudspeaker. But if I combine the inches of exterior dimensions with the ounces of the weight, what measurement do I have? Cubic inches? Cubic ounces? For example, Klipsch Cornwalls at 3 tall x 2 wide x 1 deep is 10368 cubic inches (divided by 12 is 864 cubic inches, divided by 12 again is 72 what? cubic feet?) Add 100 pounds weight and the answer is what? 172 cubic pounds? See what I getting at?

Try Klipsch Khorns. At 52 tall, 31.25 wide, average depth to 21.375, that is 34, 693 inches (divided by 12 is 2891, divided by 12 again is 240 cubic feet). plus 167 pounds, is what? 407 what? But do you see the point? Whatever number that is, the Khorns, at 407 cubic inches/pounds, is a 2.3 times larger loudspeaker than the Cornwalls (at 172 whatever). Se what I am getting at?

3.gif

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Colin,

Sounds to me like you want the density of the overall speaker, not the mass. What you want to do is divide the weight of the speaker, by it's total volume. So if you have a speaker that has a weight of 100lbs, with a volume of 1000 cubic inches, then the density is 0.1 lbs per cubic inch. You should be able to compare speaker densities quite easily this way, except for those odd shaped speakers (what is the volume of say...an Avant Garde speaker???).

-PB

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On 11/22/2002 10:07:22 AM Colin wrote:

Thats for all the replies, but I am seeking nothing so fancy as what you suggest. The weight of a loudspeaker seems to make a big difference in the sound, usually because of the dampening effect of the construction. I am trying to get an idea of the mass of a loudspeaker, compared to other loudspeakers, in order to have a rough idea of something other than mere size.

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You are attempting to rate systems based on a weight/volume basis. This might correlate indirectly to cost. Absolute weight does have merit especially when transducers are concerned and, in comparing enclosures of similar proportions your weight/volume metric might have some value as an indicator of quality. For example the adage, "Not all heavy transformers are good but all good transformers are heavy" can be applied to drivers and enclosures too.

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John, I agree with you. In fact, years ago I had the opportunity to buy at a discount, commercial speakers in a showroom theater originally built for high quality by Eastman Kodak. They were in place behind the walls and were offered to me at $3,800 a piece... but to my ear they sounded terrible!.. and were replaced by a pair that I bought on sale for $500... with less mass but far greater appeal.

By-the-way, since the Forum format has changed, I do not know how to get photos in as you have done in your post. It seems that you did it through the Klipsch web site and the file was about 858k. Care to share? -HornEd

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"the mass of a body determines the extent of attraction (i.e. the strength of the

gravitational field)."

john, that depends what you mean by "extent of attraction". the mass of a body doesn't determine acceleration. in a vacuum anyway that's a constant. it does determine velocity, momentum & force though as far as i know. but that's as far as i'm going. 9.gif

btw, how is something correlated indirectly? did you mean inversely?

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On 11/22/2002 2:08:29 PM boa12 wrote:

john, that depends what you mean by "extent of attraction".the mass of a body doesn't determine acceleration

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Boa-I did not mention acceleration. the acceleration of an object falling thru the Earths gravitational field as it approachs the Earth's surface is fixed at 9.8 m/sec2.This value is however a function of the Earth's mass.

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