622:(a) The principal display panel of a food in package form shall bear a declaration of the net quantity of contents. This shall be expressed in the terms of weight, measure, numerical count, or a combination of numerical count and weight or measure. The statement shall be in terms of fluid measure if the food is liquid, or in terms of weight if the food is solid, semisolid, or viscous, or a mixture of solid and liquid; except that such statement may be in terms of dry measure if the food is a fresh fruit, fresh vegetable, or other dry commodity that is customarily sold by dry measure. If there is a firmly established general consumer usage and trade custom of declaring the contents of a liquid by weight, or a solid, semisolid, or viscous product by fluid measure, it may be used. Whenever the Commissioner determines that an existing practice of declaring net quantity of contents by weight, measure, numerical count, or a combination in the case of a specific packaged food does not facilitate value comparisons by consumers and offers opportunity for consumer confusion, he will by regulation designate the appropriate term or terms to be used for such commodity.
20:
378:
410:
question (though one may perhaps have some trouble with the practical aspects of accurately weighing something individually in that condition). If one were however to weigh a small wading pool that someone then entered and began floating in, they would find that the full weight of the person was being borne by the pool and, ultimately, the scale underneath the pool. Whereas a buoyant object (on a properly working scale for weighing buoyant objects) would weigh less, the
366:
528:
290:
594:
about 9.8 m/s. In trade and commerce and everyday use, the term "weight" is often used as a synonym for "mass." The "net mass" or "net weight" declared on a label indicates that the package contains a specific amount of commodity exclusive of wrapping materials. The use of the term "mass" is predominant throughout the world, and is becoming increasingly common in the United States. (Added 1993)
556:-based scales (single-pan devices), one is having one's weight (gravitational force) measured; and variations in the strength of the gravitational field affect the reading. In practice, when such scales are used in commerce or hospitals, they are often adjusted on-site and certified on that basis, so that the mass they measure, expressed in pounds or kilograms, is at the desired level of accuracy.
552:
the needle to diverge from the "balanced" (null) point. These balances could be moved from Earth's equator to the poles and give exactly the same measurement, i.e. they would not spuriously indicate that the doctor's patient became 0.3% heavier; they are immune to the gravity-countering centrifugal force due to Earth's rotation about its axis. But if one steps onto spring-based or digital
219:) dominate and the influence of gravity is a negligible factor, the behavior of objects remains consistent even where gravity is relatively weak. For instance, billiard balls on a billiard table would scatter and recoil with the same speeds and energies after a break shot on the Moon as on Earth; they would, however, drop into the pockets much more slowly.
128:
536:
831:
Assumptions: An air density of 1160 g/m, an average density of a human body (with collapsed lungs) equal to that of water, and variations in barometric pressure rarely exceeding ±22 torrs (2.9 kPa). Assumptions primary variables: An altitude of 194 meters above mean sea level (the worldwide
593:
The mass of an object is a measure of the object’s inertial property, or the amount of matter it contains. The weight of an object is a measure of the force exerted on the object by gravity, or the force needed to support it. The pull of gravity on the earth gives an object a downward acceleration of
510:
Whenever a high-precision scale (or balance) in routine laboratory use is calibrated using stainless steel standards, the scale is actually being calibrated to conventional mass; that is, true mass minus 150 ppm of buoyancy. Since objects with precisely the same mass but with different densities
551:
at a doctor’s office, they are having their mass measured directly. This is because balances ("dual-pan" mass comparators) compare the gravitational force exerted on the person on the platform with that on the sliding counterweights on the beams; gravity is the force-generating mechanism that allows
438:
The mass of "weightless" (neutrally buoyant) balloons can be better appreciated with much larger hot air balloons. Although no effort is required to counter their weight when they are hovering over the ground (when they can often be within one hundred newtons of zero weight), the inertia associated
434:
in the physical sciences, and when all macro‑size objects larger than dust particles are immersed in fluids on Earth, they have some degree of buoyancy. In the case of either a swimmer floating in a pool or a balloon floating in air, buoyancy can fully counter the gravitational weight of the
405:
and can float about the house a meter or two off the floor. In such a state, there are moments when the balloon is neither rising nor falling and—in the sense that a scale placed under it has no force applied to it—is, in a sense perfectly weightless (actually as noted below, weight has merely been
222:
In the physical sciences, the terms "mass" and "weight" are rigidly defined as separate measures, as they are different physical properties. In everyday use, as all everyday objects have both mass and weight and one is almost exactly proportional to the other, "weight" often serves to describe both
206:
is pushed horizontally on a level, smooth surface, and continues in horizontal motion. This is quite distinct from its weight, which is the downwards gravitational force of the bowling ball one must counter when holding it off the floor. The weight of the bowling ball on the Moon would be one-sixth
89:
Material objects at the surface of the Earth have weight despite such sometimes being difficult to measure. An object floating freely on water, for example, does not appear to have weight since it is buoyed by the water. But its weight can be measured if it is added to water in a container which is
603:
When used in this handbook, the term "weight" means "mass". The term "weight" appears when inch-pound units are cited, or when both inch-pound and SI units are included in a requirement. The terms "mass" or "masses" are used when only SI units are cited in a requirement. The following note appears
389:
Usually, the relationship between mass and weight on Earth is highly proportional; objects that are a hundred times more massive than a one-liter bottle of soda almost always weigh a hundred times more—approximately 1,000 newtons, which is the weight one would expect on Earth from an object with a
502:
alloys with densities of about 8,000 kg/m, which occupy greater volume than those made of platinum-iridium, which have a density of about 21,550 kg/m. For convenience, a standard value of buoyancy relative to stainless steel was developed for metrology work and this results in the term
409:
Again, unlike the effect that low-gravity environments have on weight, buoyancy does not make a portion of an object's weight vanish; the missing weight is instead being borne by the ground, which leaves less force (weight) being applied to any scale theoretically placed underneath the object in
94:
in air. However the weight of the balloon and the gas inside it has merely been transferred to a large area of the Earth's surface, making the weight difficult to measure. The weight of a flying airplane is similarly distributed to the ground, but does not disappear. If the airplane is in level
118:
is constant, as long as no energy or matter is added to the object. For example, although a satellite in orbit (essentially a free-fall) is "weightless", it still retains its mass and inertia. Accordingly, even in orbit, an astronaut trying to accelerate the satellite in any direction is still
90:
entirely supported by and weighed on a scale. Thus, the "weightless object" floating in water actually transfers its weight to the bottom of the container (where the pressure increases). Similarly, a balloon has mass but may appear to have no weight or even negative weight, due to
349:, convert the mass of objects like concrete and automobiles (expressed in kilograms) to a force in newtons (by multiplying by some factor around 9.8; 2 significant figures is usually sufficient for such calculations) to derive the load of the object. Material properties like
503:"conventional mass". Conventional mass is defined as follows: "For a mass at 20 °C, ‘conventional mass’ is the mass of a reference standard of density 8,000 kg/m which it balances in air with a density of 1.2 kg/m." The effect is a small one, 150
435:
object being weighed, for a weighing device in the pool. However, as noted, an object supported by a fluid is fundamentally no different from an object supported by a sling or cable—the weight has merely been transferred to another location, not made to disappear.
486:(the science of measurement), the precision mass standards for calibrating laboratory scales and balances are manufactured with such accuracy that air density is accounted for to compensate for buoyancy effects. Given the extremely high cost of
849:) stainless (ie 18% Chromium, 8% Nickel); the other, named CH-1, is a more complex alloy that could be roughly designated as CrNiMo30-25-2 (chemical composition is 29.9% Cr, 25.1% Ni, 2.2% Mo, 1.45% Mn, 0.53 Si, 0.2% Cu, 0.07% C, 0.0019% P).
238:
for a tire in kilograms, refers to weight; that is, the force due to gravity. Before the late 20th century, the distinction between the two was not strictly applied in technical writing, so that expressions such as "molecular weight" (for
102:, which is the tendency of an object to not change its current state of motion (to remain at constant velocity) unless acted on by an external unbalanced force. Gravitational "weight" is the force created when a mass is acted upon by a
406:
redistributed along the Earth's surface so it cannot be measured). Though the rubber comprising the balloon has a mass of only a few grams, which might be almost unnoticeable, the rubber still retains all its mass when inflated.
106:
and the object is not allowed to free-fall, but is supported or retarded by a mechanical force, such as the surface of a planet. Such a force constitutes weight. This force can be added to by any other kind of force.
223:
properties, its meaning being dependent upon context. For example, in retail commerce, the "net weight" of products actually refers to mass, and is expressed in mass units such as grams or ounces (see also
610:
When used in this law (or regulation), the term "weight" means "mass." (See paragraph V. and W. in
Section I., Introduction, of NIST Handbook 130 for an explanation of these terms.) (Added 1993) 6"
47:, though these are in fact different concepts and quantities. Nevertheless, one object will always weigh more than another with less mass if both are subject to the same gravity (i.e. the same
754:, thus affecting measurements performed with a precision of 1%. Whereas 10% of the speed of light is exceedingly fast in most contexts, it is not "close to the speed of light".
832:
median altitude of human habitation), an indoor temperature of 23 °C, a dewpoint of 9 °C, and 760 mmHg (101 kPa) sea level–corrected barometric pressure.
439:
with their appreciable mass of several hundred kilograms or more can knock fully grown men off their feet when the balloon's basket is moving horizontally over the ground.
458:
is too small to be of any consequence in day-to-day activities. For instance, buoyancy's diminishing effect upon one's body weight (a relatively low-density object) is
507:
for stainless steel mass standards, but the appropriate corrections are made during the manufacture of all precision mass standards so they have the true labeled mass.
511:
displace different volumes and therefore have different buoyancies and weights, any object measured on this scale (compared to a stainless steel mass standard) has
119:
required to exert force, and needs to exert ten times as much force to accelerate a 10‑ton satellite at the same rate as one with a mass of only 1 ton.
573:
909:
681:
301:
When an object's weight (its gravitational force) is expressed in "kilograms", this actually refers to the kilogram-force (kgf or kg-f), also known as the
306:
305:(kp), which is a non-SI unit of force. All objects on the Earth's surface are subject to a gravitational acceleration of approximately 9.8 m/s. The
614:
U.S. federal law, which supersedes this handbook, also defines weight, particularly Net Weight, in terms of the avoirdupois pound or mass pound. From
446:, which states that the buoyancy force is equal to the weight of the fluid that the object displaces. If this fluid is air, the force may be small.
491:
95:
flight, the same weight-force is distributed to the surface of the Earth as when the plane was on the runway, but spread over a larger area.
615:
565:
629:
See also 21CFR201 Part 201.51 – "Declaration of net quantity of contents" for general labeling and prescription labeling requirements.
519:
degree of buoyancy. In high-accuracy work, the volume of the article can be measured to mathematically null the effect of buoyancy.
420:
becomes heavier by the value of object's full mass once the object is added. Since air is a fluid, this principle applies to object
956:
668:
373:
in which an object is immersed (gas or liquid), the buoyant force on an object is equal to the weight of the fluid it displaces.
86:, where gravity is stronger; and very small in space, far from significant sources of gravity, but it always has the same mass.
576:(NIST) have defined the use of mass and weight in the exchange of goods under the Uniform Laws and Regulations in the areas of
390:
mass slightly greater than 100 kilograms. Yet, this is not always the case and there are familiar objects that violate this
427:
systems as well; large volumes of air—and ultimately the ground—supports the weight a body loses through mid-air buoyancy.
864:
498:
mass standard in France that defined the magnitude of the kilogram), high-quality "working" standards are made of special
397:
A common helium-filled toy balloon is something familiar to many. When such a balloon is fully filled with helium, it has
274:
247:
338:
Engineers and scientists understand the distinctions between mass, force, and weight. Engineers in disciplines involving
941:
705:
693:
317:. Thus the kilogram-force is defined as precisely 9.80665 newtons. In reality, gravitational acceleration (symbol:
154:
32:
569:
696:
for a discussion of mass in this context. An object or particle does not have to be traveling very close to the
787:
184:
443:
846:
145:
property; that is, the tendency of an object to remain at constant velocity unless acted upon by an outside
377:
728:
487:
346:
19:
78:, the product of its mass and the gravitational field strength there. The object's weight is less on
212:
48:
809:
m/s is the same rate of change in velocity as 3.6 km/h per second (≈2.2 mph per second).
737:
207:
of that on the Earth, although its mass remains unchanged. Consequently, whenever the physics of
482:
in barometric pressure rarely affect a person's weight more than ±1 part in 30,000. However, in
329:
and subsurface density; these variations are typically only a few tenths of a percent. See also
188:
923:
Specifications, Tolerances, and Other
Technical Requirements for Weighing and Measuring Devices
401:—a force that opposes gravity. When a toy balloon becomes partially deflated, it often becomes
888:
504:
442:
Buoyancy and the resultant reduction in the downward force of objects being weighed underlies
309:
fixed the value of standard gravity at precisely 9.80665 m/s so that disciplines such as
246:
Because mass and weight are separate quantities, they have different units of measure. In the
216:
878:
868:
768:
402:
382:
527:
289:
842:
819:
732:
638:
499:
365:
350:
342:
297:
relief. This image has been normalized to remove variation due to differences in latitude.
270:
235:
131:
Matter's mass strongly influences many familiar kinetic properties, such as the motion of
682:
What are the differences between mass, weight, force and load? (FAQ – Mass & Density)
313:
would have a standard value for converting units of defined mass into defined forces and
951:
883:
852:
845:
stainless steel artifacts were used for comparison. One, named D2, is similar to 18-8 (
697:
548:
544:
259:
240:
841:
For example, for the recalibration of the US National
Prototype Kilogram in 1985, two
946:
935:
648:
385:
has no weight for the men to support but still retains great inertia due to its mass.
354:
255:
196:
132:
75:
818:
Objects the size of small dust particles, or smaller, are so strongly influenced by
266:
225:
203:
176:
150:
114:
of an object varies in proportion to the strength of the gravitational field, its
430:
The effects of buoyancy do not just affect balloons; both liquids and gases are
294:
278:
263:
262:
is also a unit of force typically used in the measure of weight. Similarly, the
103:
98:
A better scientific definition of mass is its description as being a measure of
63:
767:(the science of measurement), the acceleration of Earth’s gravity is taken as
58:" in an object (though "matter" may be difficult to define), but weight is the
805:, velocity changes an additional 1 meter per second. An acceleration of 1
643:
625:(b)(1) Statements of weight shall be in terms of avoirdupois pound and ounce.
331:
764:
577:
553:
535:
483:
326:
310:
231:
892:
616:
21CFR101 Part 101.105 – Declaration of net quantity of contents when exempt
873:
398:
322:
314:
251:
173:
91:
71:
127:
455:
141:
99:
531:
A balance-type weighing scale: Unaffected by the strength of gravity.
339:
83:
55:
44:
539:
Load-cell based bathroom scale: Affected by the strength of gravity.
526:
431:
376:
370:
146:
67:
59:
24:
18:
293:
Gravity anomalies covering the
Southern Ocean are shown here in
79:
40:
28:
604:
where the term "weight" is first used in a law or regulation.
515:
conventional mass measured; that is, its true mass minus an
454:
Normally, the effect of air buoyancy on objects of normal
277:, is a unit of mass, and its related unit of force is the
234:
rating on automobile tires, which specifies the maximum
857:
Journal of
Research of the National Bureau of Standards
353:
are measured and published in terms of the newton and
285:
Converting units of mass to equivalent forces on Earth
921:
National
General Conference on Weights and Measures,
853:"Recalibration of the US National Prototype Kilogram"
157:
and an important formula that sprang from his work,
70:'s surface, an object whose mass is exactly one
822:that they are no longer influenced by buoyancy.
345:(force on a structure due to gravity), such as
54:In scientific contexts, mass is the amount of "
580:and engine fuel quality in NIST Handbook 130.
574:National Institute of Standards and Technology
910:International Organization of Legal Metrology
8:
468:that of gravity (for pure water it is about
357:(a unit of pressure related to the newton).
31:. Weight varies due to different amount of
906:International Recommendation OIML R33
669:Basic Metrology for ISO 9000 Certification
307:General Conference on Weights and Measures
882:
872:
741:, relativistic mass is 0.5% greater than
187:(about one-tenth the acceleration due to
43:of an object is often referred to as its
718:) to vary measurably from its rest mass
534:
364:
288:
126:
660:
600:Use of the Terms "Mass" and "Weight."
492:international prototype of the kilogram
258:is the basic unit of force. The non-SI
450:Buoyancy effects of air on measurement
523:Types of scales and what they measure
23:Mass and weight of a given object on
7:
566:United States Department of Commerce
564:In the United States of America the
139:Mass is (among other properties) an
254:is the basic unit of mass, and the
82:, where gravity is weaker; more on
16:Distinction between mass and weight
14:
780:), which is defined as precisely
62:exerted on an object's matter by
738:The Special Theory of Relativity
478:that of gravity). Furthermore,
680:National Physical Laboratory:
381:A hot air balloon when it has
191:) when acted upon by a force,
1:
865:US Government Printing Office
803:for every second that elapses
560:Use in United States commerce
248:International System of Units
35:whereas mass stays the same.
185:meter per second per second
973:
694:Mass in special relativity
583:NIST Handbook 130 states:
211:(mass, velocity, inertia,
74:weighs approximately 9.81
33:gravitational acceleration
667:de Silva, G.M.S. (2002),
570:Technology Administration
392:mass / weight
490:mass standards like the
957:Conceptual distinctions
729:Lorentz transformations
671:, Butterworth-Heinemann
321:) varies slightly with
202:Inertia is seen when a
168:an object with a mass,
794:(m/s). The expression
627:
612:
590:"Mass" and "Weight."
540:
532:
386:
374:
347:structural engineering
298:
226:Pound: Use in commerce
136:
36:
851:Davis, R. N. (1985).
620:
585:
543:When one stands on a
538:
530:
444:Archimedes' principle
380:
368:
292:
130:
39:In common usage, the
22:
874:10.6028/jres.090.015
275:U.S. customary units
942:Concepts in physics
750:at only 9.96%
361:Buoyancy and weight
269:, used in both the
104:gravitational field
49:gravitational field
925:, NIST Handbook 44
541:
533:
387:
375:
369:Regardless of the
299:
243:) are still seen.
230:. Conversely, the
217:elastic collisions
151:Sir Isaac Newton's
137:
37:
863:(4). Washington:
792:per square second
706:relativistic mass
403:neutrally buoyant
394:proportionality.
964:
926:
919:
913:
903:
897:
896:
886:
876:
839:
833:
829:
823:
816:
810:
808:
800:
799:
791:
786:
783:
779:
769:standard gravity
763:In professional
761:
755:
749:
726:
717:
690:
684:
678:
672:
665:
488:platinum-iridium
477:
476:
472:
467:
466:
462:
426:
425:
418:
417:
393:
383:neutral buoyancy
167:
972:
971:
967:
966:
965:
963:
962:
961:
932:
931:
930:
929:
920:
916:
904:
900:
850:
840:
836:
830:
826:
820:Brownian motion
817:
813:
806:
797:
795:
789:
784:
781:
778:
775:
762:
758:
748:
745:
725:
722:
713:
691:
687:
679:
675:
666:
662:
657:
639:Apparent weight
635:
578:legal metrology
562:
525:
500:stainless steel
474:
470:
469:
464:
460:
459:
452:
423:
421:
415:
413:
391:
363:
351:elastic modulus
287:
271:Imperial system
236:structural load
209:recoil kinetics
189:Earth's gravity
158:
125:
17:
12:
11:
5:
970:
968:
960:
959:
954:
949:
944:
934:
933:
928:
927:
914:
898:
834:
824:
811:
776:
756:
746:
723:
698:speed of light
685:
673:
659:
658:
656:
653:
652:
651:
646:
641:
634:
631:
561:
558:
524:
521:
451:
448:
362:
359:
286:
283:
260:kilogram-force
241:molecular mass
155:laws of motion
133:billiard balls
124:
121:
15:
13:
10:
9:
6:
4:
3:
2:
969:
958:
955:
953:
950:
948:
945:
943:
940:
939:
937:
924:
918:
915:
911:
907:
902:
899:
894:
890:
885:
880:
875:
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866:
862:
858:
854:
848:
844:
838:
835:
828:
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821:
815:
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804:
793:
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766:
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753:
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739:
734:
730:
721:
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711:
707:
703:
699:
695:
689:
686:
683:
677:
674:
670:
664:
661:
654:
650:
649:Pound (force)
647:
645:
642:
640:
637:
636:
632:
630:
626:
623:
619:
617:
611:
609:
605:
601:
599:
595:
591:
589:
584:
581:
579:
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559:
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550:
546:
537:
529:
522:
520:
518:
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508:
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497:
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457:
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153:337-year-old
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57:
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50:
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34:
30:
26:
21:
922:
917:
905:
901:
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856:
837:
827:
814:
802:
772:
759:
751:
742:
736:
735:1905 paper,
719:
714:
709:
701:
688:
676:
663:
628:
624:
621:
613:
607:
606:
602:
597:
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582:
563:
545:balance-beam
542:
516:
512:
509:
495:
479:
453:
441:
437:
429:
416:fluid system
411:
408:
396:
388:
337:
330:
318:
302:
300:
245:
224:
221:
208:
204:bowling ball
201:
192:
180:
169:
163:
159:
140:
138:
115:
111:
109:
97:
88:
53:
38:
801:means that
295:false-color
279:pound-force
264:avoirdupois
177:accelerates
51:strength).
936:Categories
843:austenitic
733:Einstein’s
727:. Per the
712:(or γ
704:, for its
655:References
644:Gravimeter
572:, and the
480:variations
332:Gravimetry
250:(SI), the
232:load index
110:While the
771:(symbol:
765:metrology
554:load cell
484:metrology
327:elevation
315:pressures
311:metrology
213:inelastic
195:, of one
183:, at one
172:, of one
66:. At the
893:34566154
847:type 304
633:See also
399:buoyancy
323:latitude
303:kilopond
252:kilogram
174:kilogram
162:=
149:. Under
142:inertial
123:Overview
92:buoyancy
72:kilogram
884:6664201
867:: 267.
782:9.80665
608:NOTE 1:
517:unknown
473:⁄
463:⁄
456:density
343:loading
100:inertia
76:newtons
64:gravity
891:
881:
807:
796:"1 m/s
790:
788:meters
785:
568:, the
547:-type
432:fluids
412:object
355:pascal
340:weight
256:newton
197:newton
112:weight
84:Saturn
56:matter
45:weight
952:Force
549:scale
371:fluid
267:pound
147:force
68:Earth
60:force
25:Earth
947:Mass
889:PMID
731:and
692:See
273:and
215:and
116:mass
80:Mars
41:mass
29:Mars
27:and
879:PMC
869:doi
513:its
505:ppm
496:the
475:770
465:860
424:air
938::
908:,
887:.
877:.
861:90
859:.
855:.
708:,
700:,
618::
598:W.
588:V.
335:.
325:,
281:.
199:.
179:,
164:ma
912:.
895:.
871::
798:"
777:n
773:g
752:c
747:0
743:m
724:0
720:m
715:m
710:M
702:c
494:(
471:1
461:1
422:/
414:/
319:g
228:)
193:F
181:a
170:m
166:,
160:F
135:.
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