# What is energy physical quantity

Physical quantities are always the product of a numerical value with a unit. A typical time specification is about one second. The international size system has seven basic sizes: length, mass, time, electrical current, temperature, amount of substance and light intensity. A base quantity cannot be expressed in terms of other base quantities.

### Overview of the units of measurement

Physical quantities are given in units of measurement with unique values ​​according to the international system of units. The following units of measurement often appear in connection with energy:

### Joules

The unit joule is used for the quantitative measurement of all forms of energy, including work and the amount of heat. It is named after the English physicist James Prescott Joule (1818-1889). With the energy of one joule, the power of one watt can be produced for one second.

1 Y = 1 Ws

### power

The power indicates which amounts of energy are converted in a certain time. Their unit is joules per second, also called watt after the Scottish "inventor" of the steam engine.

The average power of a horse is around 500 watts (W), a diesel locomotive has an output of up to 3,000 kilowatts.

The following applies: 1 W = 1 J / s

### Kilowatt hour

We speak of kilowatt hour (kWh) when we measure electrical energy, where one kilowatt hour corresponds to 3,600 kilojoules:

1 kWh = 3,600,000 J = 3.6 megajoules (MJ)

With one kilowatt hour of electricity you can iron around 15 shirts or toast around 130 slices of bread.

The smaller unit of the kilowatt hour is the watt second (Ws).

1 kWh = 3.6 * 10 million Ws = 3.6 * 10⁶ Ws = 3.6 MJ

#### Old units in this context

Since 1977 the units of calories for heat and horsepower for power are no longer permitted. For reasons of clarity, however, the energy industry continues to frequently use the hard coal unit (SKE), which corresponds to the average energy content of one ton of hard coal:

1 t SCE = 29.3 billion J = 29.3 gigajoules (GJ)

The unit joule is used for the quantitative measurement of all forms of energy, including work and the amount of heat. It is named after the English physicist James Prescott Joule (1818-1889). With the energy of one joule, the power of one watt can be produced for one second.

1 Y = 1 Ws

The power indicates which amounts of energy are converted in a certain time. Their unit is joules per second, also called watt after the Scottish "inventor" of the steam engine.

The average power of a horse is around 500 watts (W), a diesel locomotive has an output of up to 3,000 kilowatts.

The following applies: 1 W = 1 J / s

We speak of kilowatt hour (kWh) when we measure electrical energy, where one kilowatt hour corresponds to 3,600 kilojoules:

1 kWh = 3,600,000 J = 3.6 megajoules (MJ)

With one kilowatt hour of electricity you can iron around 15 shirts or toast around 130 slices of bread.

The smaller unit of the kilowatt hour is the watt second (Ws).

1 kWh = 3.6 * 10 million Ws = 3.6 * 10⁶ Ws = 3.6 MJ

#### Old units in this context

Since 1977 the units of calories for heat and horsepower for power are no longer permitted. For reasons of clarity, however, the energy industry continues to frequently use the hard coal unit (SKE), which corresponds to the average energy content of one ton of hard coal:

1 t SCE = 29.3 billion J = 29.3 gigajoules (GJ)