võimsusmõõtme

Võimsusmõõtme, literally translated as "unit of power", is the measurement of the rate at which work is performed or energy is transferred. In physics, power is defined as the derivative of work with respect to time, or equivalently as the rate of change of energy over time. The concept is essential for describing how quickly energy can be utilized or generated in mechanical, electrical, thermal, or other systems.

In the International System of Units (SI) the fundamental unit of power is the watt, symbol W. One watt equals one joule per second and was named after James Watt in recognition of his work with steam engines. SI prefixes allow convenient scaling of the watt: kilowatts (kW), megawatts (MW), milliwatts (mW), gigawatts (GW), and so forth, providing a standardized language for all fields that quantify power.

Other units have been historically important. The mechanical horsepower, defined as 550 foot‑pounds per second or roughly 745.7 watts, was introduced by James Watt to express the performance of steam engines. In engineering contexts metric horsepower (0.7355 kW) and traditional horsepower variants still appear. Electrical consumption is commonly billed in kilowatt‑hours, a unit of energy, illustrating the relationship between power (rate) and energy (accumulated quantity).

Power measurement is crucial across physics, engineering, and everyday life. From designing motors and generators to evaluating heating systems and measuring energy bills, the unit of power informs efficiency analysis, design standards, and economic decisions. Conversion between units—such as 1 hp equals 745.7 W—allow comparisons among devices and systems worldwide.