Talk:Weight

Weigh as a compound word

I have reverted User:Wendy.krieger's edit for three reasons:

1. Weigh/weight is not like the examples listed. In the examples, the first word is an adjective while weigh is a transitive verb.
2. In this sense, everyday and legal contexts reflect the true meaning of the word, is incorrect. The true meaning of the word matches the scientific usage.
3. The scientific use is better described as heft (heave/heft), is not only a violation of WP:NPOV and possibly WP:OR but it is incorrect. Heave implies an upward motion of the object while to weigh something is usually a static process.

WikiDMc (talk) 00:36, 14 October 2011 (UTC)

The 'Oxford Dictionary of English Etymology' Edited by C.T.Onions, gives 'weight' as a measure determined by weighing. Since weighing is used to determine mass, then this is what is thus implied. The old english 'wiht' (ME wight), refers to a thing, animal, entity, matter, in any case, not a force. One ought not necessarily take scientific usage as being linguistically correct. (Electrical) displacement, which is used for the vector D, actually refers to what is called polarisation (P), which is a displacement or movement of electric dipole in the direction of the flux. The ME weight is based on the long/length sequence in that it determines a measure of (rather like modern english -age does). --Wendy.krieger (talk) 08:54, 15 October 2011 (UTC)

While the origin of the word is interesting, and probably deserves some discussion in the article, it should not cloud the issue of the word's current definition which is the force measured by the act of weighing.

Any old english definitions will conflate mass and weight because at the time there was no need to distinguish between the two. Now that man is going into space, accelerating at high g-forces etc., a distinction is required and that is why pound and pound-force are two separate and different units of measure, and why weight is strictly defined as a force and not a mass.

WikiDMc (talk) 01:00, 17 October 2011 (UTC)

Buoyancy

Buoyancy, as has been noted above, is like having somebody stand next to you and pull up on your belt. You weigh less (according to the small scale you stand on) but the other guy weighs more, so some of your weight has just been moved off-scale. If you had a bigger scale platform, your weight would not change. This is not very interesting. It's the same if I put one leg on the ground and one on the scale; I have a smaller "apparent weight" then also. And finally, if I get off the scale completely, my apparent weight I suppose goes to zero. Or does it? Does anybody see my point? Is apparent weight even worth mentioning? SBHarris 03:11, 18 October 2011 (UTC)

It is worth mentioning because many textbooks mention it. (Also note, that unlike stepping of a scale, in many real world situations it is impossible to avoid buoyancy affecting weight measurements. It is therefore important to be aware of this effect.)TR 05:56, 18 October 2011 (UTC)

At least, however, could we mention that the weight in such buoyancy situations doesn't just disappear somewhere, but is conserved and transfered to a support that the scale cannot see? The only time weight disappears is when gravity or acceleration changes. All the other things that seem to affect weight, are only affecting its distribution and how our instruments are placed to capture it.

There's an old physics story about a truck which is overweight due to its load of live chickens-- a problem solved by the driver beating on the side with a bat so all the chickens take off and fly just before the truck crosses the weight scales. Would this work? No, once you understand the principle you know that hovering chickens make the truck weigh the same as when they are perched. Same for a little model airplane flying around inside the truck. Indeed a jet airliner exerts the same weight on the surface of the earth when flying as when on the runway-- it's just spread-out more. What is the "apparent weight" of a flying airplane? Zero? Or some other imaginary number that we imagine is counteracted by "lift"? SBHarris 18:47, 18 October 2011 (UTC)

weight in such buoyancy situations ... is conserved and transfered to a support that the scale cannot see

Under the gravitational definition that may be true but under the operational definition the weight cannot be "conserved" because it does not exist other than as a reading on a scale. If the reading changes then, by definition, the (operational) weight also changes. WikiDMc (talk) 02:12, 2 November 2011 (UTC)

I hardly think the "operational" definition is meant to apply to scales that mis-read, or are misused, or are somehow fooled. If you stand on a scale with only one leg, or I pull up on your belt to give a wrong number, that doesn't mean what the scale reads is your "operational weight." It means you performed the operation of weighing yourself incorrectly, and therefore your instrument gave you an incorrect number for your weight. Perhaps it gave the correct weight that you placed upon it, but that wasn't YOUR weight-- it was simply A weight. The idea that your weight is not an objective property of you, but is rather whatever the scale says it is, no matter how you choose to use the scale, is bizarre. Can you think of any other property of objects in physics that are so "operationally" defined that the number actually IS taken to be whatever the instrument says it is, no matter how you screw up in getting the instrument to interact with what it is measuring? I certainly can't. What is the point of having an instrument if there no rules on how you must use it? I believe such a thing does not even count as an instrument and whatever you are doing doesn't count as a measurement. You are rather just messing around generating random numbers. SBHarris 03:31, 2 November 2011 (UTC)

Can you think of any other property of objects in physics that are so "operationally" defined

In physics; no, I cannot. That is why in physics the operational definition is of limited relevance. Outside of physics, almost every measured quantity is treated as if the measured value is correct notably including, for this discussion, the weight of items to be traded (without correction for buoyancy due to air).

Whether in physics or outside of physics, the examples you give of someone pulling up on your belt, etc, are all examples of a poorly performed weighing procedure. The key to the operational definition is the statement, by the operation of weighing it, which implicitly assumes that the operation of weighing has been performed correctly. Your definition of "performed correctly" and my definition may differ but I think it's fairly safe to assume that nobody would consider standing on a scale while someone pulls upward on your belt a correct (or comfortable) performance of a weighing procedure. On the other hand, to weigh an object without removing buoyancy effects would be considered by me, and I assume many, to be an appropriate weighing procedure depending on the intended use of the gained data. WikiDMc (talk) 04:59, 2 November 2011 (UTC)

Well, it wouldn't be a correct procedure if you were weighing precisely (a further correction must be done, as you know from your analytical chem classes), so it's only a matter of precission. Bouyancy removes a couple of ounces from the weight of a person in normal air, and it's only because we don't care about the two ounces that we ignore it, not because we're actually using some "operational definition." If you were weighing a partly inflated balloon, or an object of low density like aerogel, we would be grossly off the mark of correctness. The point is that it's not honest to ignore bouyancy and lump it under "operational definition" when the effects are too small to care about practically, but then change your stance when they are too large to ignore. We require one view for both cases. If you're going to ignore an effect, do it for the right reason (it's too small to care about) not for the wrong reason (pretending you really only care only about what the scale says). Actually you only care what the scale says when what the scales says is nearly right. Otherwise, you ignore the scale reading and and come up with some other method, or else correct the scale reading and don't take it literally. SBHarris 05:13, 2 November 2011 (UTC)

Well, it wouldn't be a correct procedure if you were weighing precisely

That depends on the purpose for the weighing and the intended application of the result. If I am designing a rope to suspend a rock submerged under water, then I am interested in the rock's submerged weight. So I will weigh it submerged in water and I will care only about what the scale says. It is entirely precise and no corrections are required. Or I could weigh it in air, or a vacuum, and make an adjustment for how the rock's operational weight will change once submerged in water. In either case, it is the rock's operational weight when submerged in water that I am interested in, which helps to demonstrate why I think your statement it's only because we don't care about the two ounces that we ignore it is incorrect. Sometimes we ignore it because we care about the force required to support a person in air, not their mass.

IMO, the operational weight of an object is subjective, or at least situation dependent, and whether the operation used to determine the weight is appropriate is also subjective, according to the user of the information. This fits well with the definition of, the force measured by the operation of weighing it without any caveats regarding the method, accuracy or situation of the weighing.

Further, I do not know of any source that mentions a vacuum when defining the operational definition, so cannot support wikipedia implying in any way that a vacuum is required to obtain a precise operational weight or that a correction to the force measured is required (for buoyancy). Even reference 7, Galili, does not seem to mention a vacuum even though it is referenced in support of the statement ...in theory, an object will always be weighed in a vacuum...'

As for analytical chem, is that not because we are interested in mass rather than weight?

WikiDMc (talk) 05:55, 2 November 2011 (UTC) (edited 08:20)

Sensation_of_Weight

i am quite sure that the "the vestibular system, a three-dimensional set of tubes in the inner ear." is used to tell acceleration and balance. as my perception is impaird at the moment, and i cannot tell if the vehicle i am in starts to move slowly unless it hits a bump, and i must rely on my eyes and the pressure under my feet for balance. as for "sensation of weight", i would think you would tell by using your muscles, by perceiving the task requireing more/less effort to lift or move, ie yourself. — Preceding unsigned comment added by 58.169.182.218 (talk) 21:32, 19 December 2011 (UTC)

Too long an introduction for its overall length

Although the overall length is far longer than the lead section, it still strikes me as being overly long. Some of that text should be moved into one of the sections below. Pagen HD (talk) 10:26, 26 January 2012 (UTC)

Shortened it. Having trouble getting the weight in bold -- I think maybe there's some wrong somewhere else on the page that's messing up the parser, but I can't seem to get it to work. Nobody Ent 12:23, 26 January 2012 (UTC)

Appreciate the quick response. Pagen HD (talk) 16:57, 26 January 2012 (UTC)