potential機械能(動能和位能)

1、EnergyBy Yeung Chung Kuen (05996130) (12/03/2006)Revised by Mak1What is Energy ? Basic Definitions.Forms of Energy.A Short History of Energy.Dangerousness of Energy.Renewable Energy.Resources Related to Energy.Outline2What is energy ? Energy makes change; it does things for us. It moves cars along t

2、he road and boats over the water. It bakes a cake in the oven and keeps ice frozen in the freezer. It plays our favorite songs on the radio and lights our homes. It makes our bodies grow and allows our minds to think. .3Basic DefinitionsA very good definition of energy is:Energy is the ability to do

3、 work. In common sense, work is get things done. In physics, work is force x displacement, W = Fs.4Forms of EnergyMechanical( Kinetic and potential)機械能(動能和位能)Chemical 化學能Heat 熱能Electric 電能Light 光能Sound 聲能Nuclear 核能 People have learned how to change energy from one form to another so that we can do w

4、ork more easily and live more comfortably.5Potential EnergyKinetic energy6Mechanical Energy(槓鈴) A weightlifter exerts a force to lift a barbell.The kinetic energy of the barbell changes to the potential energy of the barbell.7Work done by machine = changes in mechanical energy of the load.8Chemical

5、Energy9Chemical Heat +Light Energy1011Light/Heat Energy 12Electric/Light/Sound Energy13Light Energy14Sound/Light/Heat/Mechanical Energy15Nuclear Energy by FissionNuclear power plantsNuclear fission:A large nucleus splits into several small nuclei when bumped by a neutron and energy is released in th

6、is process. Sources: 16Nuclear fusion1718A Short History of Energy The Old Days Before the industrial revolution(工業(yè)革命), our energy needs were modest(適度的 ). 19ExamplesFor heat, we relied on the sun - and burned wood, straw, and dried dung(糞肥) when the sun failed us. For transportation, the muscle of

7、horses and the power of the wind in our sails took us to every corner of the world. For work, we used animals to do jobs that we couldnt do with our own labor. Water and wind drove the simple machines that ground our grain and pumped our water.20B.C.500,000-300,000 Use of fireMan started to use fire

8、 a half million years ago. Ancient people knew the fire through lightning, forest-fire, explosion of volcano and so on. Fire can protect them from dangerous animals, warm them in a cold night, lighten the darkness and harden earthenware(陶器 ) .They wanted to maintain convenient fire to use it anytime

9、. At first they kept the fire which was occurred by forest fire by transferring to wood pieces. 21Forest Fire22But it was difficult to control fire by this method. A wise man thought. Producing fire by ourselves is the better way!“Luxury is the mother of invention Man has invented the methods to pro

10、duce and control fire more easily.Use of fire 23B.C.5000? Invention of cart with wheels.Man invented and developed tools continuously. But, to carry tools and the materials was tough job. Man invented cart with wheels in order to carry loads easily. This was the first step to mechanical energy“ whic

11、h developed civilization(文明 ) rapidly .24B.C.-3000Traditional boat was improved to sailboat in order to utilize wind and drive boat faster.This was a great turning point in the meaning that man utilized wind as motion energy, as well as windmill(風車) which is used in some area nowadays.25B.C.2000?- W

12、ar using armsAfter man established civilization and made city, each city had their own army to guard their people from enemies. In the war, they use arms such as a stone bow(弓). Man began to use energy for destroying.26B.C.600 Discovery of electricityMan discovered electricity 2500 years ago. Amber(

13、琥珀 ) which was rubbed generated static electricity which attracted light materials. Electric energy“ which is most familiar to us in the history of energy was discovered at that time.However modern technology for controlling electric energy was established at a much later time, say until Volta inven

14、ted the Voltaic cell at 1799.But man continued to develop the techniques of utilizing energy not being satisfied.27 7th Century Invention of windmill (風車 )Windmill is one of very important inventions in the Medieval Ages(中世紀).Windmill brought the improvement in efficiency of job and the spread of te

15、chnology to operate some machines at the same time by using cranks and gears. (曲柄 ) (齒輪 ) The development of mechanical energy“ was accelerated hereinafter.2816th century- The Industrial Revolution and further development1. Steam engine(蒸汽機)29The development of utilizing technology of mechanical ene

16、rgy was accelerated at the speed which mankind had never experienced by the invention of steam engine. Steam engine brought people railways, power plant(發(fā)電廠), modern manufacturing plants and so on. Steam engine30The development of shipbuilding technology, telegraphic communication (電報Marconi 1874-19

17、37), railway technology, and the invention of airplane in the first half of 19th century made people to communicate worldwide2. Birth of international network31End of 19th century: Birth of power plantInvention of electric light bulb (Edison 1847-1931) is a milestone of modernization in 19th century

18、. Electric light was rapidly spread in the industrial countries around the world with increasing number of power plants, and the age of electric energy had come.32A.D.1914-1918World War 1The First World War in which 32 countries participated was a war using technological armament such as submarine,

19、aircraft, carrier, poison gas, machine gun. Many lives were sacrificed in the war, showing the dark side of energy and technology.33A.D.1939-1945World War 2The World War 2 is a very important milestone in the utilizataion of energy, because nuclear arms were used for the first time in the war. It sh

20、ows that energy and technology can destroy the civilization, if they are used in wrong way.34Nuclear Explosion35A.D.1986 Accident at Chernobyls nuclear power plantThis accident teach us that we should consider also dangerousness in thinking the use of energy.We cannot say absolutely safety“ in the f

21、ield of nuclear energy.36A.D.19971998Rush of nuclear explosion testsNorth Korea, India, Pakistan are the countries which made nuclear explosion tests in recent years. Nuclear armament should not be appreciated even if it is for self-defense.The 20th century is the maturation period of high-technology and the beginning ages of new energy.However, we must always consider the adverse effect of using energy.37 All of our main energy techn