1. ENERGY NOTES MS. FISHER 2014

2. CHAPTER THREE NOTES: ENERGY Section 3.1-Energy exists in different forms Just about everything you see happening around you involves energy. Energy is the ability to cause change. Different forms of energy have different uses. (Ex: the flow of electrical energy through a wire causes a cool, dark bulb to get hot and glow. The energy of the wind causes a flag to flutter.)

3. SCIENTISTS CLASSIFY ENERGY INTO MANY FORMS. EACH FORM CAUSES A CHANGE IN A DIFFERENT WAY. Mechanical energy is the energy that moves objects.  Ex: the energy you use to put a book on a shelf or turn a key in a car’s ignition

4. Sound energy is vibration in the air caused from vibrations in a solid, liquid, or gas.  People detect sound because it causes vibrations within structures of their ears.  Sound cannot travel through empty space.

5. Chemical Energy is stored in the chemical composition of matter.  The amount of chemical energy in a substance depends on the types and arrangement of atoms in the substance.  Ex: Chemical energy produces heat when wood or gasoline burns. Chemical energy stored in the foods you eat is used by the cells in your body.

6. Thermal Energy is the total amount of energy from the movement of particles in matter.

7. Electromagnetic Energy is transmitted through space in the form of electromagnetic waves.  Electromagnetic waves can travel through empty space.  Ex: Electromagnetic waves include visible light, x-rays, and microwaves.

8. Nuclear Energy holds nuclear particles together in the center of an atom.  Nuclear energy is released when the nucleus of an atom breaks apart or the nuclei of two atoms join together.  Ex: nuclear energy released from the fusing of small nuclei to form larger nuclei keeps the Sun burning.

9. KINETIC ENERGY AND POTENTIAL ENERGY ARE THE TWO GENERAL TYPES OF ENERGY. Anything that is moving, such as a car that is being driven or an atom in the air, has kinetic energy. Kinetic energy is the energy of motion.  It depends on an object’s mass and the speed at which the object is moving.  Kinetic energy increases as mass increases. If a bowling ball and a soccer ball were moving at the same speed, the bowling ball would have more kinetic energy because of its greater mass.  Kinetic energy increases as speed increases. If two identical bowling balls were rolling along at different speeds, the faster one would have more kinetic energy because of its greater speed.

11. All matter also has potential energy, or energy that is stored and can be released at a later time.  Potential energy is the stored energy that an object has due to its position or chemical composition.  An objects mass and its height above ground determine how much potential energy it has due to gravity.  Ex: A ball held in your hands has potential energy because of its potential to fall.  Objects can have potential energy from several sources such as gravity and chemical composition.

13. All matter also has potential energy, or energy that is stored and can be released at a later time.  Potential energy is the stored energy that an object has due to its position or chemical composition.  An objects mass and its height above ground determine how much potential energy it has due to gravity.  Ex: A ball held in your hands has potential energy because of its potential to fall.  Objects can have potential energy from several sources such as gravity and chemical composition.

14. SECTION 3.2-ENERGY CAN CHANGE FORMS BUT IS NEVER LOST. Potential energy can be changed into kinetic energy and back into potential energy.  Consider the example of a ski jumper (pg. 79).  At first the jumper has potential energy due to his position at the top of the hill.  Some of his potential energy is changed into kinetic energy as he moves down the hill. Kinetic energy moves him down the hill.  His kinetic energy is changed back into potential energy when he leaves the ramp and rises into the air.  As the jumper falls to the ground, his potential energy changes into kinetic energy.

16.  Label the diagram below with:  High PE & Low KE, Low PE & High KE, Transform KE to PE, Transform PE to KE (some may be used more than once)

17. Energy is often converted from one form to another in order to meet everyday needs.  Energy in water that is stored behind a dam is changed into electrical energy (See p. 80-81)  Potential energy becomes kinetic energy, kinetic energy becomes electrical energy.  Energy of moving water is renewable.

20.  Almost all energy on Earth began as electromagnetic energy from the Sun.  Plants convert the electromagnetic energy of sunlight into chemical energy as they grow.  This energy, stored by plants hundreds of millions of years ago, is the energy found in fossil fuels, such as petroleum, coal, and natural gas.  Chemical energy in fossil fuels is converted into other forms of energy for specific uses.  Fossil fuels are not renewable.

21. Energy is always conserved.  The law of conservation of energy states that energy can neither be created nor destroyed.  Although it may appear in some instances that energy is gained or lost, it is really only changed in form.  When a soccer ball is kicked, the amount of energy the soccer player gives to the ball by kicking it is equal to the energy the ball gains. The energy the ball loses is equal to the amount of energy that is transferred to the universe as sound energy and heat as the ball slows down.

22. Energy conversions may produce unwanted forms of energy.  When energy changes form, the amount of useful energy is almost always less than the total amount of energy.  Ex: With an electric fan, the amount of electrical energy used is greater than the kinetic energy of the moving fan blades. Because energy is always conserved, some of the electrical energy flowing into the fan’s motor is changed into unusable/unwanted forms, such as sound and heat.

23.  Energy efficiency is a measurement of usable energy after an energy conversion.  The more energy efficient a fan is, the more electrical energy it turns into kinetic energy in the moving blades.

24. SECTION 3.3-TECHNOLOGY IMPROVES THE WAYS PEOPLE USE ENERGY In many common energy conversions, most of the wasted energy is released as heat.  One example is the common light bulb. Only about 5% of the electrical energy that enters a light bulb is converted into light. 95% of the electrical energy turns into unwanted forms of energy such as heat.  Research to replace light bulbs with a more energy- efficient source of light resulted in the LED.  LEDs convert almost all of the electrical energy they use into light.

25.  A large percentage of gasoline’s chemical energy is not converted into a car’s kinetic energy.  Some of the kinetic energy is wasted as heat from the car’s engine, tires, and brakes.  Fuel injectors monitor and control the amount of gasoline that is fed into a car’s engine. This precise control of fuel provides a significant increase in the distance a car can travel on a tank of gasoline.  Hybrid cars use both gasoline and electrical energy from batteries. These cars are very fuel efficient.

26. Technology improves the use of energy resources.  Much of the energy used on Earth comes from fossil fuels, but the supply of fossil fuels is limited.  Solar energy and wind energy are used on a small scale to generate electrical energy.  Advantages to using solar and wind energy are that the supply is not limited and they do not produce harmful waste that fossil fuels do.

27.  Solar cells are made of several layers of light-sensitive materials, which convert sunlight directly into electrical energy.  The materials used to make them are expensive.  Large numbers of solar cells produce only a small amount of electrical energy.  Windmills have been used to generate electrical energy.  Advances in capturing and using wind energy have helped to improve its efficiency and usefulness.  One way to better capture the wind’s energy has been to build huge windmill farms in areas that receive a consistent amount of wind.

28. LIGHTBULB REPLACEMENT GAME http://www.kidsenergyzone.com/games/activitiesdetail63.cfm?activityid=19 http://www.kidsenergyzone.com/games/ http://www.powerhousekids.com/kids/007011 TYPES OF RENEWABLE ENERGY WIND ENERGY QUIZ