The kilojoule, abbreviated as kJ, is a unit of energy in the International System of Units. While it may not be as commonly recognized as calories in everyday conversation, the kilojoule is actually the standard metric unit for quantifying energy. Fascinatingly, 1 kilojoule is equivalent to 0.239 calories, making it a handy unit for converting nutritional information, especially in countries that primarily use the metric system.
Interestingly, the term “joule” is named after the English physicist James Prescott Joule, who studied the nature of heat and discovered its relationship to mechanical work. This unit has applications far beyond nutrition, including physics, chemistry, and engineering, where it measures various types of energy transformations, from kinetic to thermal. Understanding kilojoules can deepen our appreciation of energy, highlighting the intricate balances that power our world and our bodies.
The watt-hour (Wh) is a unit of energy that measures the amount of electricity consumed or generated over time. It is the energy equivalent to one watt of power consumed for one hour. While electricity bills commonly display kilowatt-hours (kWh), understanding watt-hours can give you clearer insights into the energy efficiency of your household. For instance, a 60-watt incandescent light bulb running for one hour uses 60 watt-hours of electricity, while an energy-efficient LED bulb might only use around 10 watt-hours for the same illumination.
Interestingly, the concept of the watt-hour helps in comprehending renewable energy systems. Solar panels, for example, are rated in watts, but their output over time is often expressed in watt-hours or kilowatt-hours. Knowing this can help you assess how much energy your solar array could generate or your battery storage can hold, emphasizing the real value of alternative energy sources.
Kilojoules | Watt-hours |
---|---|
0
kJ
|
0
Wh
|
10
kJ
|
2.77778
Wh
|
20
kJ
|
5.55556
Wh
|
30
kJ
|
8.33333
Wh
|
40
kJ
|
11.11111
Wh
|
50
kJ
|
13.88889
Wh
|
60
kJ
|
16.66667
Wh
|
70
kJ
|
19.44444
Wh
|
80
kJ
|
22.22222
Wh
|
90
kJ
|
25
Wh
|
100
kJ
|
27.77778
Wh
|
110
kJ
|
30.55556
Wh
|
120
kJ
|
33.33333
Wh
|
130
kJ
|
36.11111
Wh
|
140
kJ
|
38.88889
Wh
|
150
kJ
|
41.66667
Wh
|
160
kJ
|
44.44444
Wh
|
170
kJ
|
47.22222
Wh
|
180
kJ
|
50
Wh
|
190
kJ
|
52.77778
Wh
|
200
kJ
|
55.55556
Wh
|
210
kJ
|
58.33333
Wh
|
220
kJ
|
61.11111
Wh
|
230
kJ
|
63.88889
Wh
|
240
kJ
|
66.66667
Wh
|
250
kJ
|
69.44444
Wh
|
260
kJ
|
72.22222
Wh
|
270
kJ
|
75
Wh
|
280
kJ
|
77.77778
Wh
|
290
kJ
|
80.55556
Wh
|
300
kJ
|
83.33333
Wh
|
310
kJ
|
86.11111
Wh
|
320
kJ
|
88.88889
Wh
|
330
kJ
|
91.66667
Wh
|
340
kJ
|
94.44444
Wh
|
350
kJ
|
97.22222
Wh
|
360
kJ
|
100
Wh
|
370
kJ
|
102.77778
Wh
|
380
kJ
|
105.55556
Wh
|
390
kJ
|
108.33333
Wh
|
400
kJ
|
111.11111
Wh
|
410
kJ
|
113.88889
Wh
|
420
kJ
|
116.66667
Wh
|
430
kJ
|
119.44444
Wh
|
440
kJ
|
122.22222
Wh
|
450
kJ
|
125
Wh
|
460
kJ
|
127.77778
Wh
|
470
kJ
|
130.55556
Wh
|
480
kJ
|
133.33333
Wh
|
490
kJ
|
136.11111
Wh
|
500
kJ
|
138.88889
Wh
|
510
kJ
|
141.66667
Wh
|
520
kJ
|
144.44444
Wh
|
530
kJ
|
147.22222
Wh
|
540
kJ
|
150
Wh
|
550
kJ
|
152.77778
Wh
|
560
kJ
|
155.55556
Wh
|
570
kJ
|
158.33333
Wh
|
580
kJ
|
161.11111
Wh
|
590
kJ
|
163.88889
Wh
|
600
kJ
|
166.66667
Wh
|
610
kJ
|
169.44444
Wh
|
620
kJ
|
172.22222
Wh
|
630
kJ
|
175
Wh
|
640
kJ
|
177.77778
Wh
|
650
kJ
|
180.55556
Wh
|
660
kJ
|
183.33333
Wh
|
670
kJ
|
186.11111
Wh
|
680
kJ
|
188.88889
Wh
|
690
kJ
|
191.66667
Wh
|
700
kJ
|
194.44444
Wh
|
710
kJ
|
197.22222
Wh
|
720
kJ
|
200
Wh
|
730
kJ
|
202.77778
Wh
|
740
kJ
|
205.55556
Wh
|
750
kJ
|
208.33333
Wh
|
760
kJ
|
211.11111
Wh
|
770
kJ
|
213.88889
Wh
|
780
kJ
|
216.66667
Wh
|
790
kJ
|
219.44444
Wh
|
800
kJ
|
222.22222
Wh
|
810
kJ
|
225
Wh
|
820
kJ
|
227.77778
Wh
|
830
kJ
|
230.55556
Wh
|
840
kJ
|
233.33333
Wh
|
850
kJ
|
236.11111
Wh
|
860
kJ
|
238.88889
Wh
|
870
kJ
|
241.66667
Wh
|
880
kJ
|
244.44444
Wh
|
890
kJ
|
247.22222
Wh
|
900
kJ
|
250
Wh
|
910
kJ
|
252.77778
Wh
|
920
kJ
|
255.55556
Wh
|
930
kJ
|
258.33333
Wh
|
940
kJ
|
261.11111
Wh
|
950
kJ
|
263.88889
Wh
|
960
kJ
|
266.66667
Wh
|
970
kJ
|
269.44444
Wh
|
980
kJ
|
272.22222
Wh
|
990
kJ
|
275
Wh
|
1000
kJ
|
277.77778
Wh
|
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