Joule

From Freepedia

The joule (symbol: J) is the SI unit of energy, or work. It is named in honor of the physicist James Prescott Joule (1818–1889).

Contents 1 Definition 2 Conversions 3 Multiples 4 See also

Definition

The joule is a derived unit defined as the work done, or energy required, to exert a force of one newton for a distance of one metre, so the same quantity may be referred to as a newton metre or newton-metre (also with meter spelling), with the symbol N·m or N m. It can also be written as kg·m²·s⁻². However, the newton metre is usually used as a measure of torque, not energy.

One joule is also:

• the work required to move an electric charge of one coulomb through an electrical potential difference of one volt; or one coulomb volt, with the symbol C·V.

• the work done to produce power of one watt continuously for one second; or one watt second (compare kilowatt-hour), with the symbol W·s

Conversions

1 joule is equal to:

• 10 000 000 erg (ergs)
• c. 0.239 cal (calorie) (small calories)
• 0.0002390 Calorie or kilocalorie (food)
• 4.184 J – 1 thermochemical calorie (exact)
• 4.1868 J – 1 International Table calorie (exact)
• c. 0.000 948 BTU (British thermal unit)
• c. 0.738 ft·lbf (foot pound force)
• c. 23.7 ft·pdl (foot poundals)
• 0.0000002778 kilowatt-hour
• 0.0002778 watt-hour
• 0.0098692 litre-atmosphere
• 1 J – The energy required to lift a small apple (102 g) one metre against Earth's gravity

Multiples

Multiple	Name	Symbol		Multiple	Name	Symbol
100	joule	J
101	decajoule	daJ		10–1	decijoule	dJ
102	hectojoule	hJ		10–2	centijoule	cJ
103	kilojoule	kJ		10–3	millijoule	mJ
106	megajoule	MJ		10–6	microjoule	µJ
109	gigajoule	GJ		10–9	nanojoule	nJ
1012	terajoule	TJ		10-12	picojoule	pJ
1015	petajoule	PJ		10-15	femtojoule	fJ
1018	exajoule	EJ		10–18	attojoule	aJ
1021	zettajoule	ZJ		10–21	zeptojoule	zJ
1024	yottajoule	YJ		10–24	yoctojoule	yJ

See also

• conversion of units
• SI prefixes
• orders of magnitude
• orders of magnitude (energy)
• electronvolt
• watt-hour