Define energy.
The correct answer and explanation is:
Energy is the capacity to do work or produce change. It exists in various forms, including kinetic energy, potential energy, thermal energy, chemical energy, electrical energy, and more. Energy is a fundamental concept in physics, which governs the behavior of matter and the processes that occur within the universe.
In scientific terms, energy cannot be created or destroyed; it can only be transformed from one form to another. This principle is known as the Law of Conservation of Energy. For example, when you push an object, the energy you exert is transferred to the object, giving it kinetic energy. Similarly, when you lift an object against gravity, the energy used in lifting it is stored as potential energy. When energy is transferred or transformed, it may lose some of its usable form as heat due to inefficiencies in the process.
The unit of energy in the International System of Units (SI) is the joule (J), though other units such as calories, kilowatt-hours, and electron volts are also used in different contexts. Energy can be measured in various ways depending on the context. For instance, the energy in food is measured in calories, while electrical energy is measured in kilowatt-hours.
Energy plays a crucial role in virtually every process in the natural world, from the cellular processes in living organisms to large-scale phenomena like the movement of planets. The Sun, for example, provides energy to Earth in the form of light and heat, which is essential for life on the planet. Likewise, all machines, vehicles, and technologies rely on energy to function. Understanding how energy works and how it can be conserved is vital for addressing challenges related to sustainability, such as reducing energy consumption and mitigating climate change.