能量概念

能量是必须传递给物体以对其做功或加热的定量属性。它是守恒量；能量守恒定律规定能量可以转换形式，但不能创造或销毁。

介绍

Energy is fundamental to all physical processes and technological applications. Understanding energy units and conversions is essential for engineering, physics, and everyday applications from household electricity to industrial processes.

历史

The concept of energy evolved through the work of scientists like James Joule, who established the mechanical equivalent of heat. The joule was adopted as the SI unit of energy in honor of his contributions to thermodynamics and energy conservation.

关键单位

Joule (J)

The SI unit of energy, equal to the work done by a force of one newton over one meter.

Kilowatt-hour (kWh)

Equal to 3.6 MJ, commonly used for electrical energy consumption billing.

Calorie (cal)

Equal to 4.184 J, historically used for heat energy, now mainly in nutrition.

British Thermal Unit (BTU)

Equal to 1,055 J, used in heating and air conditioning applications.

Electron volt (eV)

Equal to 1.602 × 10⁻¹⁹ J, used in atomic and particle physics.

Therm

Equal to 105.5 MJ, used for natural gas energy content.

应用

  • Electrical power generation and distribution
  • Building heating and cooling systems
  • Transportation fuel efficiency calculations
  • Food and nutrition energy content labeling
  • Industrial process energy optimization
  • Renewable energy system design and analysis

Energy Relationships

E = mc², KE = ½mv², PE = mgh

Energy-mass equivalence, kinetic energy, and gravitational potential energy equations.