Practical examples[edit]

One joule in everyday life represents approximately:

the energy required to lift a small apple (with a mass of approximately 100 g) vertically through one metre of air.

the energy released when that same apple falls one metre to the ground.

the energy required to accelerate a 1 kg mass at 1 ms2 through a 1 m distance in space.

the heat required to raise the temperature of 1 g of water by 0.24 K.[6]

the typical energy released as heat by a person at rest every 1/60 second (approximately 17 ms).[7]

the kinetic energy of a very slowly (0.2 m/s or 0.72 km/h).

the kinetic energy of a 56 g tennis ball moving at 6 m/s (22 km/h).[8]

the kinetic energy of an object with at 2 1.4 m/s.

The amount of electricity required to light a 1 watt LED for 1 s.

Since the joule is also a watt-second and the common unit for electricity sales to homes is the kWh (kilowatt-hour), a kWh is thus 1000 (kilo) watt 3600 seconds = 3.6 MJ (megajoules).

One joule can also be defined as:

The work required to move an electric charge of one coulomb through an of one volt, or one ‘”coulomb volt” (CV). This relationship can be used to define the volt.

The work required to produce one watt of power for one second, or one “watt second” (Ws) (compare kilowatt hour – 3.6 megajoules). This relationship can be used to define the watt.

Conversions[edit]

Main article: Conversion of units of energy

1 joule is equal to:

1107 erg (exactly)

6.241509741018 eV

0.2390 cal (gram calories)

2.390104 kcal (food calories)

9.4782104 BTU

0.7376 ftlb

23.7 ftpdl (foot-poundal)

2.7778107 kilowatt-hour

2.7778104 watt-hour

9.8692103 latm (litre-atmosphere)

11.12651015 gram (by way of )

11044 foe (exactly)

Units defined exactly in terms of the joule include:

1 thermochemical calorie = 4.184 J[14]

1 International Table calorie = 4.1868 J[15]

1 watt hour = 3600 J (or 3.6 kJ)

1 kilowatt hour = 3.6106 J (or 3.6 MJ)

1 watt second = 1 J

1 ton TNT = 4.184 GJ