What Is Energy?
Energy is a critical aspect of modern life. It includes the electricity, heat and other types of energy used to power our homes, businesses, and transportation. Energy as a scientific principle is found in many sources and forms.
The scientific definition of energy is the ability to do work. Work is the transfer of energy to move an object a certain distance. The rate at which work is done is called power. The ratio of work and time determines the amount of power used. For example, imagine that two people start at the bottom of a mountain with the goal of reaching the top. The first person hikes to the top in a short amount of time. The second person scales the rocks to the top which takes a much longer amount of time. The same amount of work was done by both (they reached the top of the mountain), but the hiker has more power since the distance traveled was completed in a shorter amount of time.
Potential versus Kinetic Energy
Energy occurs in two primary states, potential and kinetic. Potential energy is stored energy. Kinetic energy is the release of the potential energy to create motion, ultimately to do work. Work is the transfer of energy to move an object a certain distance.
An example of potential energy being transformed into kinetic energy to do work is a pump storage facility at a power plant that uses water to generate electricity. In this facility, water is pumped to a holding area where it is stored. The stored water has the potential to do work, or potential energy. When released, the flow of water, or kinetic energy, downstream is doing work. A turbine downstream turns due to the work of the water.
Forms of Energy
Energy, whether in the potential or kinetic state, occurs in different forms . These forms can be transformed from one to another to generate energy necessary to do work. Our lives depend on many types of energy transformations. What are these forms? Here are a few definitions and examples of energy transformation:
Electrical energy is the flow of electrons along a circuit. The movement of electrons creates an electric current which generates electricity. Electrical energy can be transformed into:
• mechanical energy by an elevator
• thermal energy by a space heater.
Thermal energy is the use of heat as the source of energy. Thermal energy can be transformed into:
• mechanical energy using a steam engine.
Chemical energy is generated from chemical reactions in which the chemical bonds of a substance are broken and rearranged to form new molecules that can provide energy. Chemical energy can be transformed into:
• thermal energy by burning wood
• mechanical energy through digestion of food in our bodies
• electrical energy by burning coal.
Radiant energy comes from a light source, such as the sun. Energy released from the sun is in the form of photons. These tiny particles, invisible to the human eye, move in a way similar to a wave. Radiant energy can be transformed into:
• electrical energy using solar panels.
Mechanical energy refers to an object that is doing work by being in motion. Mechanical energy can be transformed into:
• electrical energy using a wind turbine
• thermal energy using a refrigerator.
Nuclear energy is generated when parts of the atoms in certain materials split off in a controlled environment. This process produces heat (thermal energy) for various uses, including electricity generation.
Nuclear energy can be transformed into:
• thermal energy in a fission reactor
• electrical energy in a nuclear power plant.