Chapter 10: Forms of Energy Ms. Johnson Foundations

Objectives Energy is the ability to do work. There are two states of energy: potential energy is stored energy based on position or chemical makeup; kinetic energy is the energy of motion. Energy occurs in the following forms: mechanical, chemical, nuclear, sound, heat, electrical, and light. The Law of Conservation of Energy states that energy cannot be created or destroyed, it can only be transformed into other forms of energy. Energy transformation occurs when energy is changed from one form to another form. When people transform energy for some purpose, some unwanted form of energy is always produced, which is not useful for that purpose.

Vocabulary Energy Potential energy Kinetic energy Mechanical energy Sound Chemical energy Nuclear energy Heat energy Electrical energy Light Law of Conservation of Energy

ENERGY BASICS Chapter 10: Forms of Energy

Energy Energy: the ability to do work. Ex. A flowing river has the ability to move a boat. Ex. A moving car has the ability to carry people from one place to another. This means that both examples possess some form of energy.

States of Energy There are two basic states of energy: Potential and Kinetic Potential Energy: stored energy that an object has because of its position or its chemical composition. Ex. A rock on a cliff has potential energy because of its position. Kinetic Energy: energy that an object has when it is moving. Ex. A rock falling off a cliff has kinetic energy. The faster an object moves, the more kinetic energy it has.

Examples

States of Energy Potential energy may be changed into kinetic energy when motion is produced. Ex. Water held behind a dam has potential energy. Releasing that water, transforms the energy to kinetic energy. Kinetic energy may also be changed into potential energy. Ex. When a ball is throw in the air, its kinetic energy of motion is changed into potential energy as the ball climbs higher above the ground. At it’s highest point, the ball is motionless (even if for a split-second) and has only potential energy.

States of Energy

Forms of Energy Both potential and kinetic energy exist in many forms. The following table lists some examples of different forms of energy. Form of EnergyExample MechanicalFan SoundBell ChemicalCandle NuclearNuclear Reactor HeatToaster ElectricalGenerator LightLamp (bulb)

Mechanical Energy Mechanical Energy: The energy with which moving objects perform work. Ex. A jack lifting a car, hammering a nail, pedals on a bike

Chemical Energy Chemical Energy: energy stored in certain substances because of their chemical makeup. When these substances are burned, the energy is released. Ex. Coal, oil, propane gas, food

Nuclear Energy Nuclear Energy: the energy stored within the nucleus (center) of an atom. This energy can be released by joining atoms together or splitting atoms apart.

Heat Energy Heat Energy: produced by the molecular motion of matter. All matter contains heat energy. Ex. Rubbing your hands together, burning a match, burning fuel

Electrical Energy Electrical Energy: produced by the flow of electrons through a conductor, such as a wire. Ex. Computers, lightbulbs, washing machine, generators

Light Energy Light Energy: a form of radiant energy that moves in waves. Light as a form of energy can be demonstrated by using a magnifying glass to burn a hole in a leaf.

NATURE OF ENERGY TRANSFORMATION Chapter 10: Forms of Energy

Law of Conservation of Energy Law of Conservation of Energy: states the energy can neither be created nor destroyed but can only be transformed from one type of energy into one or more other types of energy. Ex. When electricity passes through a lightbulb, not all of the electricity is converted into light energy, some of it gets converted into heat energy. Either way, the total amount of energy entering the lightbulb is equal to the amount of energy being released as light and heat.

Law of Conservation of Energy

Energy Transformations Energy can be changed (transformed) from one form into another. Ex. When you take a bus to school. Chemical energy in gasoline is changed into mechanical energy that turns the wheels on the bus. Ex. You get to school and the bell rings. Electrical energy is transformed into sound energy.

Unwanted Energy Sometimes when we transform energy, an unwanted form of energy is produced. Ex. A car motor is designed to change chemical energy into mechanical energy Running motors become hot though, due to friction. So some of the original chemical energy gets converted into unwanted heat energy. This unwanted energy is also referred to as “lost energy.” (Keep in mind because of the law of conservation, it is not actually lost, just transformed into energy that is not useful for the purpose).

QUESTIONS? Chapter 10: Forms of Energy