490:) by the serving size (usually in grams, milliliters or fluid ounces). An energy unit commonly used in nutritional contexts within non-metric countries (e.g. the United States) is the "dietary calorie," "food calorie," or "Calorie" with a capital "C" and is commonly abbreviated as "Cal." A nutritional Calorie is equivalent to a thousand chemical or thermodynamic calories (abbreviated "cal" with a lower case "c") or one kilocalorie (kcal). Because food energy is commonly measured in Calories, the energy density of food is commonly called "caloric density". In the metric system, the energy unit commonly used on food labels is the kilojoule (kJ) or megajoule (MJ). Energy density is thus commonly expressed in metric units of cal/g, kcal/g, J/g, kJ/g, MJ/kg, cal/mL, kcal/mL, J/mL, or kJ/mL.
614:
the speed of the Earth around the Sun is about 30 km/s, a comet's speed relative to the Earth can range from 12 to 72 km/s, the latter corresponding to 2592 MJ/kg. If a comet with this speed fell to the Earth it would gain another 63 MJ/kg, yielding a total of 2655 MJ/kg with a speed of 72.9 km/s. Since the equator is moving at about 0.5 km/s, the impact speed has an upper limit of 73.4 km/s, giving an upper limit for the specific energy of a comet hitting the Earth of about 2690 MJ/kg.
756:
549:, lower the energy density of foods as well. A moderate energy density would be 1.6 to 3 calories per gram (7–13 kJ/g); salmon, lean meat, and bread would fall in this category. Foods with high energy density have more than three calories per gram (>13 kJ/g) and include crackers, cheese, chocolate, nuts, and fried foods like potato or tortilla chips.
613:
have even more energy, typically moving with respect to the Sun, when in our vicinity, at about the square root of two times the speed of the Earth. This comes to 42 km/s, or a specific energy of 882 MJ/kg. The speed relative to the Earth may be more or less, depending on direction. Since
540:
times as much energy. Fats contain more carbon-carbon and carbon-hydrogen bonds than carbohydrates or proteins, yielding higher energy density. Foods that derive most of their energy from fat have a much higher energy density than those that derive most of their energy from carbohydrates or
525:
content is the most important factor in computing energy density. In general, proteins have lower energy densities (≈16 kJ/g) than carbohydrates (≈17 kJ/g), whereas fats provide much higher energy densities (≈38 kJ/g),
205:
482:
Energy density is the amount of energy per mass or volume of food. The energy density of a food can be determined from the label by dividing the energy per serving (usually in
149:
586:, because gravity changes the kinetic and potential specific energies of a vehicle in ways that are independent of the mass of the vehicle, consistent with the
456:, the special names for the respective units should be used, that is, the name gray should be used instead of joules per kilogram for the unit of absorbed dose
49:
442:
964:
940:
713:
591:
910:
501:
for calculation). In aerobic environments, this typically requires oxygen as an input and generates waste products such as
162:
100:
868:
621:
comet (50 km in diameter) had hit Earth, it would have vaporized the oceans and sterilized the surface of Earth.
1021:
1016:
992:
924:
810:
790:
319:, which is related to the maximum specific energy of rotation an object can have without flying apart due to
278:
746:
601:
falling on the Earth from outside the Earth's gravitational well is at least one half the square of the
579:
155:
1011:
409:
For a table giving the specific energy of many different fuels as well as batteries, see the article
243:
239:
741:
661:
947:
563:
Energy density is sometimes more useful than specific energy for comparing fuels. For example,
802:
701:
587:
782:
731:
541:
proteins, even if the water content is the same. Nutrients with a lower absorption, such as
335:
of a substance, which uses units such as joules per mole, or the older but still widely used
255:
916:
120:
234:, which is defined as energy per unit volume. It is used to quantify, for example, stored
8:
736:
422:
271:
267:
34:
988:
920:
806:
786:
320:
316:
251:
247:
891:
679:
667:
263:
873:
602:
564:
450:
438:
298:
725:
630:
606:
558:
502:
410:
323:. The concept of specific energy is related to but distinct from the notion of
259:
231:
1005:
969:
761:
583:
546:
542:
430:
223:
510:
487:
445:
states: "In order to avoid any risk of confusion between the absorbed dose
324:
305:
82:
853:
831:
709:
705:
498:
494:
477:
426:
347:
The following table shows the factors for conversion to J/kg of some non-
332:
309:
290:
618:
598:
521:, which make up ninety percent of the dry weight of food. Therefore,
483:
328:
294:
289:(J/kg). Other units still in use worldwide in some contexts are the
437:
is calculated for the stochastic health effect on tissues, known as
605:
of 11.2 km/s. This comes to 63 MJ/kg (15 kcal/g, or 15 tonnes
568:
286:
64:
755:
518:
506:
461:
434:
348:
336:
55:
728:, which has tables of specific energies of devices and materials
464:
instead of joules per kilogram for the unit of dose equivalent
293:
per gram (Cal/g or kcal/g), mostly in food-related topics, and
220:
93:
567:
fuel has a higher specific energy (energy per unit mass) than
429:
is the SI unit of specific energy absorbed by matter known as
297:
per kilogram in the field of batteries. In some countries the
610:
522:
493:
Energy density measures the energy released when the food is
282:
89:
60:
697:
235:
16:
Physical quantity representing energy content per unit mass
892:"Carbohydrates, Proteins, and Fats: Overview of Nutrition"
686:
is the height above the reference level (giving J/kg when
843:
Using the definition based on the thermochemical calorie.
514:
389:
301:
670:
with respect to gravity, close to Earth, per unit mass:
165:
123:
37:
751:
497:
by a healthy organism when it ingests the food (see
571:does, but a much lower volumetric energy density.
342:
200:{\displaystyle {\mathsf {L}}^{2}{\mathsf {T}}^{-2}}
199:
143:
43:
1003:
830:Using the definition based on the international
443:International Committee for Weights and Measures
582:, rather than simply energy, is often used in
983:Çengel, Yunus A.; Turner, Robert H. (2005).
982:
941:"The Okinawa Diet: Caloric Density Pyramid"
662:kinetic energy per unit mass of projectiles
597:The specific energy of an object such as a
869:"Consider caloric density for weight loss"
471:
886:
884:
866:
775:
1004:
985:Fundamentals of Thermal-Fluid Sciences
908:
509:, the only sources of food energy are
315:Specific energy has the same units as
183:
169:
803:"Handbook of Computational Chemistry"
416:
881:
678:is the acceleration due to gravity (
795:
230:, which is not to be confused with
13:
912:11th Hour: Introduction to Biology
266:of a body. Specific energy is an
14:
1033:
867:Stevens, Heidi (April 19, 2010).
821:Using the thermochemical calorie.
754:
624:
574:
343:Table of some non-SI conversions
281:unit for specific energy is the
957:
933:
656:is the speed (giving J/kg when
258:. It may also be used for the
76:kcal/g, W⋅h/kg, kW⋅h/kg, Btu/lb
902:
860:
854:"CIPM, 2002: Recommendation 2"
846:
837:
824:
815:
592:Newtonian gravitational system
312:and applied technical fields.
270:, whereas energy and mass are
226:. It is also sometimes called
1:
785:. Fairmont Press, 405 pages.
768:
714:specific heat of vaporization
700:: energies per unit mass are
433:, from which the SI unit the
783:"Boiler Operator's Handbook"
781:Kenneth E. Heselton (2004),
747:Orders of magnitude (energy)
7:
719:
10:
1038:
965:"The end of life on Earth"
801:Jerzy Leszczynski (2011),
580:Specific mechanical energy
556:
475:
228:gravimetric energy density
909:Wilson, David L. (2009).
805:. Springer, 1430 pages.
308:(Btu/lb) is used in some
154:
110:
99:
80:
70:
54:
26:
21:
1022:Mass-specific quantities
1017:Thermodynamic properties
244:specific internal energy
240:thermodynamic properties
742:Specific orbital energy
552:
702:specific heat capacity
682:as ≈9.8 m/s) and
588:conservation of energy
472:Energy density of food
242:of substances such as
201:
145:
45:
917:John Wiley & Sons
732:Power-to-weight ratio
710:specific melting heat
660:is in m/s). See also
331:, that is energy per
256:Helmholtz free energy
202:
146:
144:{\displaystyle e=E/m}
46:
272:extensive properties
163:
121:
35:
505:and water. Besides
737:Heat of combustion
423:ionising radiation
417:Ionising radiation
268:intensive property
197:
141:
84:SI base units
41:
407:
406:
321:centrifugal force
317:specific strength
252:Gibbs free energy
248:specific enthalpy
210:
209:
44:{\displaystyle e}
1029:
1012:Energy (physics)
998:
975:
974:
961:
955:
954:
952:
946:. Archived from
945:
937:
931:
930:
906:
900:
899:
896:The Merck Manual
888:
879:
878:
864:
858:
857:
850:
844:
841:
835:
828:
822:
819:
813:
799:
793:
779:
764:
759:
758:
708:difference, and
668:Potential energy
648:
646:
645:
642:
639:
539:
538:
534:
531:
354:
353:
264:potential energy
206:
204:
203:
198:
196:
195:
187:
186:
179:
178:
173:
172:
150:
148:
147:
142:
137:
114:other quantities
112:Derivations from
85:
50:
48:
47:
42:
19:
18:
1037:
1036:
1032:
1031:
1030:
1028:
1027:
1026:
1002:
1001:
995:
987:. McGraw Hill.
979:
978:
963:
962:
958:
953:on May 9, 2009.
950:
943:
939:
938:
934:
927:
907:
903:
890:
889:
882:
874:Chicago Tribune
865:
861:
852:
851:
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842:
838:
829:
825:
820:
816:
800:
796:
780:
776:
771:
760:
753:
722:
643:
640:
637:
636:
634:
633:per unit mass:
627:
603:escape velocity
577:
565:liquid hydrogen
561:
555:
536:
532:
529:
527:
480:
474:
451:dose equivalent
439:dose equivalent
419:
345:
254:, and specific
213:Specific energy
188:
182:
181:
180:
174:
168:
167:
166:
164:
161:
160:
133:
122:
119:
118:
115:
113:
83:
73:
36:
33:
32:
29:
22:Specific energy
17:
12:
11:
5:
1035:
1025:
1024:
1019:
1014:
1000:
999:
993:
977:
976:
973:. Jun 4, 2016.
956:
932:
925:
919:. p. 40.
901:
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859:
845:
836:
823:
814:
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773:
772:
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766:
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750:
749:
744:
739:
734:
729:
726:Energy density
721:
718:
717:
716:
695:
690:is in m/s and
665:
631:Kinetic energy
626:
623:
607:TNT equivalent
576:
573:
559:Energy density
557:Main article:
554:
551:
547:sugar alcohols
503:carbon dioxide
476:Main article:
473:
470:
418:
415:
411:Energy density
405:
404:
403:2.32444 kJ/kg
401:
397:
396:
393:
386:
385:
382:
378:
377:
374:
370:
369:
366:
362:
361:
360:SI equivalent
358:
344:
341:
260:kinetic energy
232:energy density
208:
207:
194:
191:
185:
177:
171:
158:
152:
151:
140:
136:
132:
129:
126:
116:
111:
108:
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104:
97:
96:
87:
78:
77:
74:
71:
68:
67:
58:
52:
51:
40:
30:
28:Common symbols
27:
24:
23:
15:
9:
6:
4:
3:
2:
1034:
1023:
1020:
1018:
1015:
1013:
1010:
1009:
1007:
996:
994:0-07-297675-6
990:
986:
981:
980:
972:
971:
970:New Scientist
966:
960:
949:
942:
936:
928:
926:9781444313222
922:
918:
914:
913:
905:
897:
893:
887:
885:
876:
875:
870:
863:
855:
849:
840:
833:
827:
818:
812:
808:
804:
798:
792:
788:
784:
778:
774:
763:
762:Energy portal
757:
752:
748:
745:
743:
740:
738:
735:
733:
730:
727:
724:
723:
715:
711:
707:
703:
699:
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693:
689:
685:
681:
677:
673:
669:
666:
663:
659:
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651:
632:
629:
628:
625:Miscellaneous
622:
620:
615:
612:
608:
604:
600:
595:
593:
589:
585:
584:astrodynamics
581:
575:Astrodynamics
572:
570:
566:
560:
550:
548:
544:
524:
520:
516:
512:
511:carbohydrates
508:
504:
500:
496:
491:
489:
488:food calories
485:
479:
469:
467:
463:
460:and the name
459:
455:
452:
448:
444:
440:
436:
432:
431:absorbed dose
428:
424:
414:
412:
402:
399:
398:
394:
391:
388:
387:
383:
380:
379:
375:
372:
371:
367:
364:
363:
359:
356:
355:
352:
350:
340:
338:
334:
330:
326:
322:
318:
313:
311:
307:
303:
300:
299:Imperial unit
296:
292:
288:
284:
280:
275:
273:
269:
265:
261:
257:
253:
249:
245:
241:
237:
233:
229:
225:
224:per unit mass
222:
218:
217:massic energy
214:
192:
189:
175:
159:
157:
153:
138:
134:
130:
127:
124:
117:
109:
105:
102:
98:
95:
91:
88:
86:
79:
75:
69:
66:
62:
59:
57:
53:
38:
31:
25:
20:
984:
968:
959:
948:the original
935:
911:
904:
895:
872:
862:
848:
839:
826:
817:
797:
777:
691:
687:
683:
680:standardized
675:
671:
657:
653:
649:
616:
609:per tonne).
596:
578:
562:
492:
481:
465:
457:
453:
446:
420:
408:
395:2.326 kJ/kg
368:4.184 MJ/kg
346:
325:molar energy
314:
276:
227:
216:
212:
211:
56:SI unit
832:steam table
706:temperature
499:food energy
495:metabolized
478:Food energy
310:engineering
291:kilocalorie
250:, specific
72:Other units
1006:Categories
811:940070710X
791:0881734357
769:References
484:kilojoules
384:3.6 MJ/kg
376:3.6 kJ/kg
339:per mole.
295:watt hours
238:and other
694:is in m).
619:Hale-Bopp
599:meteoroid
329:chemistry
190:−
156:Dimension
101:Intensive
834:calorie.
720:See also
674:, where
652:, where
569:gasoline
519:proteins
449:and the
349:SI units
337:calories
287:kilogram
856:. BIPM.
647:
635:
617:If the
535:⁄
507:alcohol
462:sievert
441:. The
435:sievert
991:
923:
809:
789:
712:, and
704:times
611:Comets
425:, the
400:Btu/lb
381:kWh/kg
365:kcal/g
221:energy
951:(PDF)
944:(PDF)
590:in a
543:fiber
523:water
373:Wh/kg
306:pound
283:joule
989:ISBN
921:ISBN
807:ISBN
787:ISBN
698:Heat
553:Fuel
517:and
515:fats
427:gray
421:For
357:Unit
333:mole
304:per
285:per
277:The
236:heat
545:or
486:or
468:."
392:/lb
390:Btu
327:in
302:BTU
262:or
219:is
215:or
106:Yes
81:In
1008::
967:.
915:.
894:.
883:^
871:.
672:gh
594:.
513:,
413:.
351::
279:SI
274:.
246:,
65:kg
997:.
929:.
898:.
877:.
692:h
688:g
684:h
676:g
664:.
658:v
654:v
650:v
644:2
641:/
638:1
537:4
533:1
530:+
528:2
466:H
458:D
454:H
447:D
193:2
184:T
176:2
170:L
139:m
135:/
131:E
128:=
125:e
103:?
94:s
92:⋅
90:m
63:/
61:J
39:e
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