Section 1: The Nature of Energy

What is energy?
- Every change that occurs—large or small—involves energy.
- When something is able to change its environment or itself, it has energy.
- Energy is the ability to cause change.
- Energy can be stored and it can move from place to place.
- Radiant energy from the Sun travels a vast distance through space to Earth, warming the planet and providing energy that enables green plants to grow.
Kinetic Energy: the energy a moving object has because of its motion.
- The kinetic energy of a moving object depends on the object’s mass and its speed.
- Joule: The SI unit of energy
Potential Energy: Stored energy due to position
- Energy doesn’t have to involve motion.
- Elastic Potential Energy: energy stored by something that can stretch or compress, such as a rubber band or spring.
- Chemical Potential Energy: Energy stored in chemical bonds
- Gravitational Potential Energy: energy stored by objects due to their position above Earth’s surface.
- According to the equation for gravitational potential energy, the GPE of an object can be increased by increasing its height above the ground.
- An object’s gravitational potential energy increases as its height increases.

Section 2: Conservation of Energy

Changing Forms of Energy
- A lightbulb is a device that transforms electrical energy into light energy and thermal energy.
- Fuel stores energy in the form of chemical potential energy.
- In the engine of a car, several energy conversions occur.
- Some energy transformations are less obvious because they do not result in visible motion, sound, heat, or light.
Conversions Between Kinetic and Potential Energy
- To understand the energy conversions that occur, it is helpful to identify the mechanical energy of a system.
- Mechanical Energy: the total amount of potential and kinetic energy in a system and can be expressed by this equation.
  - Mechanical energy is energy due to the position and the motion of an object or the objects in a system.
- Energy transformations also occur during projectile motion when an object moves in a curved path.
- Objects that can fall have gravitational potential energy.
The Law of Conservation of Energy: states that energy cannot be created or destroyed.
- Mechanical energy stays constant.
- Kinetic and potential energy simply change forms and no energy is destroyed.
- Energy can change from one form to another, but the total amount of energy never changes.
- The law of conservation of energy requires that the total amount of energy going into a hair dryer must equal the total amount of energy coming out of the hair dryer.
  - The law of conservation of energy is a universal principle that describes what happens to energy as it is transferred from one object to another or as it is transformed.
- Sometimes it is hard to see the law of conservation of energy at work.
- The total amount of energy always stays the same.
- A special kind of energy conversion—nuclear fusion—takes place in the Sun and other stars.
- Mass is converted to energy in the processes of fusion and fission.
- Another process involving the nuclei of atoms, called nuclear fission, converts a small amount of mass into enormous quantities of energy.
- In either process, fusion or fission, mass is converted to energy.
- In processes involving nuclear fission and fusion, the total amount of energy is still conserved if the energy content of the masses involved are included.
- The process of nuclear fission is used by nuclear power plants to generate electrical energy.
The Human Body - Balancing the Energy Equation
- Some of the chemical potential energy stored in your body is used to maintain a nearly constant internal temperature.
  - A portion of this energy also is converted to the excess heat that your body gives off to its surroundings.
- The complex chemical and physical processes going on in your body also obey the law of conservation of energy.
- Your body stores energy in the form of fat and other chemical compounds.
- To maintain a healthy weight, you must have a proper balance between energy contained in the food you eat and the energy your body uses.
- Your body also can use the chemical potential energy stored in fat for its energy needs.
- Every gram of fat a person consumes can supply 9 C of energy.

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Physical Science

Chapter 4: Energy

Section 1: The Nature of Energy

What is energy?
- Every change that occurs—large or small—involves energy.
- When something is able to change its environment or itself, it has energy.
- Energy is the ability to cause change.
- Energy can be stored and it can move from place to place.
- Radiant energy from the Sun travels a vast distance through space to Earth, warming the planet and providing energy that enables green plants to grow.
Kinetic Energy: the energy a moving object has because of its motion.
- The kinetic energy of a moving object depends on the object’s mass and its speed.
- Joule: The SI unit of energy
Potential Energy: Stored energy due to position
- Energy doesn’t have to involve motion.
- Elastic Potential Energy: energy stored by something that can stretch or compress, such as a rubber band or spring.
- Chemical Potential Energy: Energy stored in chemical bonds
- Gravitational Potential Energy: energy stored by objects due to their position above Earth’s surface.
- According to the equation for gravitational potential energy, the GPE of an object can be increased by increasing its height above the ground.
- An object’s gravitational potential energy increases as its height increases.

Section 2: Conservation of Energy

Changing Forms of Energy
- A lightbulb is a device that transforms electrical energy into light energy and thermal energy.
- Fuel stores energy in the form of chemical potential energy.
- In the engine of a car, several energy conversions occur.
- Some energy transformations are less obvious because they do not result in visible motion, sound, heat, or light.
Conversions Between Kinetic and Potential Energy
- To understand the energy conversions that occur, it is helpful to identify the mechanical energy of a system.
- Mechanical Energy: the total amount of potential and kinetic energy in a system and can be expressed by this equation.
  - Mechanical energy is energy due to the position and the motion of an object or the objects in a system.
- Energy transformations also occur during projectile motion when an object moves in a curved path.
- Objects that can fall have gravitational potential energy.
The Law of Conservation of Energy: states that energy cannot be created or destroyed.
- Mechanical energy stays constant.
- Kinetic and potential energy simply change forms and no energy is destroyed.
- Energy can change from one form to another, but the total amount of energy never changes.
- The law of conservation of energy requires that the total amount of energy going into a hair dryer must equal the total amount of energy coming out of the hair dryer.
  - The law of conservation of energy is a universal principle that describes what happens to energy as it is transferred from one object to another or as it is transformed.
- Sometimes it is hard to see the law of conservation of energy at work.
- The total amount of energy always stays the same.
- A special kind of energy conversion—nuclear fusion—takes place in the Sun and other stars.
- Mass is converted to energy in the processes of fusion and fission.
- Another process involving the nuclei of atoms, called nuclear fission, converts a small amount of mass into enormous quantities of energy.
- In either process, fusion or fission, mass is converted to energy.
- In processes involving nuclear fission and fusion, the total amount of energy is still conserved if the energy content of the masses involved are included.
- The process of nuclear fission is used by nuclear power plants to generate electrical energy.
The Human Body - Balancing the Energy Equation
- Some of the chemical potential energy stored in your body is used to maintain a nearly constant internal temperature.
  - A portion of this energy also is converted to the excess heat that your body gives off to its surroundings.
- The complex chemical and physical processes going on in your body also obey the law of conservation of energy.
- Your body stores energy in the form of fat and other chemical compounds.
- To maintain a healthy weight, you must have a proper balance between energy contained in the food you eat and the energy your body uses.
- Your body also can use the chemical potential energy stored in fat for its energy needs.
- Every gram of fat a person consumes can supply 9 C of energy.