Transcript Energy:
Energy Nature of Energy Energy is all around you!. You can see energy as light. And you can feel it as wind. Nature of Energy You use energy when you: hit a baseball lift your book bag. Lay on your bed and compress the mattress springs. Intro to Energy Living organisms need energy for growth and movement. Intro to Energy Energy is involved when: a bird flies. a bomb explodes. rain falls from the sky. electricity flows in a wire. Intro to Energy What is energy that it can be involved in so many different activities? Energy can be defined as the ability to do work. If an object or organism does work the object or organism uses energy. exerts a force over a distance to move an object Intro to Energy Energy and work have a direct relationship so both measured in…. joules (J)= 1 Newton- Meter work done when object is moved 1 meter by 1 Newton of force In addition to using energy to do work, objects gain energy because work is being done on them. States of Energy The most common energy conversion is the conversion between potential and kinetic energy. All forms of energy can be in either of two states: Potential Kinetic States of Energy Kinetic Energy is the energy of motion. Potential Energy is stored energy. Kinetic Energy The energy of motion is called kinetic energy. The faster an object moves, the more kinetic energy it has. The greater the mass of a moving object, the more kinetic energy it has. Kinetic energy depends on both mass and velocity. Kinetic Energy K.E. = (1/2) mass x velocity What has a greater affect of kinetic energy, mass or velocity? Why? Potential Energy Potential Energy is stored energy. Stored chemically in fuel, the nucleus of atom, and in foods. Or stored because of the work done on it: Stretching a rubber band. Winding a watch. Pulling back on a bow’s arrow. Lifting a brick high in the air. Gravitational Potential Energy Potential energy that is dependent on height is called gravitational potential energy. Gravitational Potential Energy A waterfall, a suspension bridge, and a falling snowflake all have gravitational potential energy. Gravitational Potential Energy If you stand on a 3-meter diving board, you have 3 times the G.P.E, than you had on a 1-meter diving board. Gravitational Potential Energy “The bigger they are the harder they fall” is not just a saying. It’s true. Objects with more mass have greater G.P.E. The formula to find G.P.E. is G.P.E. = Mass X Height. Elastic Potential Energy Energy that is stored due to being stretched or compressed is called elastic potential energy. Kinetic-Potential Energy Conversion Roller coasters work because of the energy that is built into the system. Initially, the cars are pulled mechanically up the tallest hill, giving them a great deal of potential energy. From that point, the conversion between potential and kinetic energy powers the cars throughout the entire ride. Kinetic vs. Potential Energy At the point of maximum potential energy, the car has minimum kinetic energy. Kinetic-Potential Energy Conversions As a basketball player throws the ball into the air, various energy conversions take place. Ball slows down Ball speeds up Forms of Energy The 6 main forms of energy are: Mechanical Thermal (Heat) Chemical Electrical Electromagnetic (Radiant -Light) Nuclear Mechanical Energy When work is done to an object, it acquires energy to move. The energy it acquires is known as mechanical energy. Involves moving parts The conversion of Potential Energy to Kinetic Energy is key Mechanical Energy When you kick a football, you give mechancal energy to the football to make it move. Mechanical Energy When you throw a balling ball, you give it energy. When that bowling ball hits the pins, some of the energy is transferred to the pins (transfer of momentum). Mechanical Energy When you eat food, you are have energy to go for a run. You are moving due to mechanical energy When a windmill’s propellers move from the wind blowing, they move due to mechanical energy When you hit a golf ball during mini golf, the golf ball moves due to mechanical energy. Thermal or Heat Energy The motion between atoms is called heat energy, because moving particles produce heat. Think about friction and what happens when you rub your hands together Changes in temperature Becoming colder and hotter are both results of Thermal Energy Chemical Energy Chemical Energy is stored in chemical bonds And when bonds are broken, the energy is given off. This energy does work Chemical Energy Fuel and food are forms of stored chemical energy. Battery Electrical Energy Electrical charges are involved They exert forces that do work It also occurs in nature Ex: lightning bolts, static electricity Electrical Energy Starts in natural gas power plant Power lines carry electrical energy into your home in the form of electricity. Electromagnetic Energy A.K.A – Radiant Light is another form of electromagnetic energy. Ultraviolet, heat, microwaves, and radar Carried by X-rays, radio waves, and laser light. Full Spectrum of light Visible light Rainbow Nuclear Energy The nucleus of an atom is the source of nuclear energy. Nuclear Energy When the nucleus splits (fission), nuclear energy is released in the form of heat energy and light energy. Nuclear energy is also released when nuclei collide at high speeds and join (fuse). Nuclear Energy The sun’s energy is produced from a nuclear fusion reaction. The light and UV Rays are the result Nuclear Energy Nuclear energy is the most concentrated form of energy. Nuclear power plants use and provide it Energy Conversion Energy can be changed from one form to another. Changes in the form of energy are called energy conversions Energy conversions All forms of energy can be converted into other forms. The sun’s energy through solar panels can be converted directly into electricity. Ex: Green plants sun’s energy (electromagnetic) starches and sugars (chemical energy). Other energy conversions In a battery, chemical energy electrical energy In a waterfall or dam Mechanical electrical energy in a generator Electric motor chemical electromagnetic mechanical energy. Energy Conversions In an automobile engine, fuel is burned to convert chemical energy into heat energy. The heat energy is then changed into mechanical energy. Cars Chemical Heat Mechanical The Law of Conservation of Energy Energy can be neither created nor destroyed by ordinary means. It can only be converted from one form to another. If energy seems to disappear, then scientists look for it – leading to many important discoveries. Natural Resources Type types Non-Renewable Renewable Non- Renewable Resources Energy resources that exist in a limited amount Cannot be replaced once used Except over millions of years Types Coal Oil/Petroleum Natural gas Fossil Fuels Fossil Fuels Fuels made underground Remains of dead plants and animals Heat from core of Earth and pressure from being buried Account for the majority of the worlds energy use Inexpensive and easily available BUT create pollution Coal Most abundant & most commonly burned fossil fuel in the world Burns very easily We get it through mining Used for heat and electricity Oil/Petroleum & Natural Gas Used for heat and electricity Very important sources of energy for transportation, farming, and other industries (factories) Get it through drilling and pumping Natural Gas Power Plants chemical energy in the gas gas is burned, releasing heat energy heat energy is used to make high-pressure steam The steam turns a turbine which transforms the heat energy to mechanical energy the turbine turns an electric generator, producing electrical energy. Renewable Resources Resources of energy exist in an unlimited amount They CAN be replaced once used Types Takes a short period of time Hydroelectric Solar Geothermal Wind NOT EFFICIENT Hydroelectric Obtained from flowing water As water flows downhill, gravitational PE KE KE is used to turn turbines connected to electric generators Dams are used to do this Solar Using the suns rays to make electricity Done through use of solar cells (panels) Every 15 min, Earth receives enough energy from sun to meet the energy needs of world for one year Geothermal Thermal (heat) energy beneath Earth’s surface. Inside Earth is hot and heats water underground Make water into steam to turn turbines of electric generators to create electricity Wind Energy gained from the wind blowing Wind turbines (fans) use the movement of air to convert wind energy into electricity in generators