potential)机械能(动能和位能)

1、EnergyBy Yeung Chung Kuen (05996130) (12/03/2022)Revised by Mak12021/5/281.What is Energy ? 2.Basic Definitions.3.Forms of Energy.4.A Short History of Energy.5.Dangerousness of Energy.6.Renewable Energy.7.Resources Related to Energy.Outline22021/5/28What is energy ? Energy makes change; it does thin

2、gs for us. It moves cars along the 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. .32021/5/28Basic DefinitionsA very good definition

3、 of energy is:Energy is the ability to do work. In common sense, work is get things done. In physics, work is force x displacement, W = Fs.42021/5/28Forms of Energy1.Mechanical( Kinetic and potential)機械能(動能和位能)2.Chemical 化學能3.Heat 熱能4.Electric 電能5.Light 光能6.Sound 聲能7.Nuclear 核能 8. People have learne

4、d how to change energy from one form to another so that we can do work more easily and live more comfortably.52021/5/28Potential EnergyKinetic energy62021/5/28Mechanical Energy(槓鈴) A weightlifter exerts a force to lift a barbell.The kinetic energy of the barbell changes to the potential energy of th

5、e barbell.72021/5/28Work done by machine = changes in mechanical energy of the load.82021/5/28Chemical Energy92021/5/28Chemical Heat +Light Energy102021/5/289、 人的价值，在招收诱惑的一瞬间被决定。21.7.1521.7.15Thursday, July 15, 202110、低头要有勇气，抬头要有低气。20:40:4320:40:4320:407/15/2021 8:40:43 PM11、人总是珍惜为得到。21.7.1520:40:43

6、20:40Jul-2115-Jul-2112、人乱于心，不宽余请。20:40:4320:40:4320:40Thursday, July 15, 202113、生气是拿别人做错的事来惩罚自己。21.7.1521.7.1520:40:4320:40:43July 15, 202114、抱最大的希望，作最大的努力。2021年7月15日星期四下午8时40分43秒20:40:4321.7.1515、一个人炫耀什么，说明他内心缺少什么。2021年7月下午8时40分21.7.1520:40July 15, 202116、业余生活要有意义，不要越轨。2021年7月15日星期四20时40分43秒20:40:4

7、315 July 202117、一个人即使已登上顶峰，也仍要自强不息。下午8时40分43秒下午8时40分20:40:4321.7.152021/5/289、 人的价值，在招收诱惑的一瞬间被决定。21.7.1521.7.15Thursday, July 15, 202110、低头要有勇气，抬头要有低气。20:40:4320:40:4320:407/15/2021 8:40:43 PM11、人总是珍惜为得到。21.7.1520:40:4320:40Jul-2115-Jul-2112、人乱于心，不宽余请。20:40:4320:40:4320:40Thursday, July 15, 202113、生

8、气是拿别人做错的事来惩罚自己。21.7.1521.7.1520:40:4320:40:43July 15, 202114、抱最大的希望，作最大的努力。2021年7月15日星期四下午8时40分43秒20:40:4321.7.1515、一个人炫耀什么，说明他内心缺少什么。2021年7月下午8时40分21.7.1520:40July 15, 202116、业余生活要有意义，不要越轨。2021年7月15日星期四20时40分43秒20:40:4315 July 202117、一个人即使已登上顶峰，也仍要自强不息。下午8时40分43秒下午8时40分20:40:4321.7.152021/5/2813202

9、1/5/28Light/Heat Energy 142021/5/28Electric/Light/Sound Energy152021/5/28Light Energy162021/5/28Sound/Light/Heat/Mechanical Energy172021/5/28Nuclear Energy by FissionNuclear power plantsNuclear fission:A large nucleus splits into several small nuclei when bumped by a neutron and energy is released i

10、n this process. 182021/5/28Nuclear fusion192021/5/28202021/5/28A Short History of Energy The Old Days Before the industrial revolution(工業革命), our energy needs were modest(適度的 ). 212021/5/28ExamplesFor heat, we relied on the sun - and burned wood, straw, and dried dung(糞肥) when the sun failed us. For

11、 transportation, the muscle of 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.222021/5/28Man started to

12、 use fire 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 i

13、t anytime. At first they kept the fire which was occurred by forest fire by transferring to wood pieces. 232021/5/28Forest Fire242021/5/28But 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

14、invented the methods to produce and control fire more easily.Use of fire 252021/5/28Man 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“ which de

15、veloped civilization(文明 ) rapidly .262021/5/28B.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.272021/5/

16、28After 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.282021/5/28Man discovered electricity 2500 years ago. Amber(琥珀 ) which was rubbed generated st

17、atic 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 invented the Voltaic cell at 1799.But m

18、an continued to develop the techniques of utilizing energy not being satisfied.292021/5/28 7th Century Invention of windmill (風車風車 )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 technology to operate som

19、e machines at the same time by using cranks and gears. (曲柄 ) (齒輪 ) The development of mechanical energy“ was accelerated hereinafter.302021/5/2816th century- The Industrial Revolution and further development1. Steam engine(蒸汽機)312021/5/28The development of utilizing technology of mechanical energy w

20、as accelerated at the speed which mankind had never experienced by the invention of steam engine. Steam engine brought people railways, power plant(發電廠), modern manufacturing plants and so on. Steam engine322021/5/28The development of shipbuilding technology, telegraphic communication (電報Marconi 187

21、4-1937), railway technology, and the invention of airplane in the first half of 19th century made people to communicate worldwide2. Birth of international network332021/5/28End of 19th century: Birth of power plantInvention of electric light bulb (Edison 1847-1931) is a milestone of modernization in

22、 19th century. 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.342021/5/28The First World War in which 32 countries participated was a war using technological armament such as submarine, ai

23、rcraft, carrier, poison gas, machine gun. Many lives were sacrificed in the war, showing the dark side of energy and technology.352021/5/28The 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 shows that energy a

24、nd technology can destroy the civilization, if they are used in wrong way.362021/5/28Nuclear Explosion372021/5/28This accident teach us that we should consider also dangerousness in thinking the use of energy.We cannot say absolutely safety“ in the field of nuclear energy.382021/5/28North 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 pe