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# Types of Energy Energy cannot be created or destroyed, but it can be transformed into other forms. ## Kinetic Energy This is the energy of objects in motion. Examples include rushing rivers and spinning tornadoes. ## Potential Energy An object has potential energy when it has the ability to...

# Types of Energy Energy cannot be created or destroyed, but it can be transformed into other forms. ## Kinetic Energy This is the energy of objects in motion. Examples include rushing rivers and spinning tornadoes. ## Potential Energy An object has potential energy when it has the ability to create another form of energy. For example, a storm cloud converts potential energy to electrical energy when it releases lightning. Water at the top of a waterfall has potential energy that is converted into kinetic energy as it falls. ## Electrical Energy This is the potential and kinetic energy carried by an electric current, which is a flow of charged particles. Electricity is useful for transporting energy from one place to another, where it can be converted to other forms, such as heat. ## Thermal Energy Thermal energy is another name for heat. It's how we measure the kinetic energy of atoms and molecules. Every object has some thermal energy, which is the tiny vibrations and movements of atoms inside the object. The faster the atoms move, the more heat is generated. ## Chemical Energy This type of potential energy is stored in the bonds that hold atoms together in a substance, like a battery. When a chemical reaction breaks these bonds, energy is released and the substance changes into something new, like electricity. For example, when gasoline burns in a car engine, chemical energy is changed to kinetic energy, which makes the car move. ## Sound Energy Sound, or acoustic energy, is carried by wave motions through the air, or other mediums. Examples of how sound is created include clapping hands, slamming doors, and vibrating violin strings. Sound energy can travel through liquids and solids. ## Radiant Energy This type of energy is carried by radiation. Light is one type of radiation; others include infrared, microwaves, and x-rays. Each type of radiation carries a specific amount of energy and can travel through space. # Conservation of Energy The way energy behaves is governed by the laws of thermodynamics. The first law states that the amount of energy in a closed system remains constant, even if it transforms into different types of energy. For example, when someone cycles up a hill, chemical energy from food is converted into kinetic energy to move the legs and pedals. This kinetic energy is then transferred to the bike's back wheel as the bike moves up the hill. Some of the chemical energy also is converted into wasted thermal energy from the body and legs. # Measuring Energy Scientists use the term "work" to describe the amount of useful energy taken or given to an object. Work involves applying a force to move an object a certain distance. The amount of energy is measured in units called joules (J). One joule is roughly equal to the energy needed to lift three apples one foot (or to move 0.45 kg one-third of a meter). # Tools of the Trade A sound pressure level (SPL) meter app on a smartphone can use the built-in microphone to measure the decibels or noise volume of sound energy. # Try This! This section describes an experiment to calculate a person's power output. It involves weighing yourself in pounds measuring the height of some stairs (in feet/meters), running up the stairs, and timing the run. Energy is calculated by multiplying your weight by the stair height and dividing the result by the time taken during the run. The results reveal the power of the body. # Powering Up The speed at which energy does its work is described as power. When a runner goes back up the track after finishing a race, they need the same amount of energy overall, however, the ability to use this energy much faster makes them exert more power. Total work done expressed in "joules", divided by the time taken to do total work, shows power. The unit of power is the watt (W). A watt is equal to one joule per second.