As shown, object A and B with mass of m1 and m2 are put on a smooth su

1.The theoretical basis of using energy method to find the natural frequency of the system is ().选项： A:Theorem of moment of momentum; B:The kinetic energy theorem; C:Law of conservation of mechanical energy; D:The momentum theorem

2.5.Object 1 has twice the mass of Object 2. Both objects have the same kinetic energy. Which of the following statements is true?选项： A:Both objects can have the same magnitude of momentum.; B:Object 1 has a momentum of greater magnitude than Object 2.; C:The magnitude of the momentum of Object 2 is four times that of Object 1.; D:All the statements are false.; E:All the statements are true.

3.Different forms of energy are interconvertible, but the total amount of energy must not be conserved.

4.Different forms of energy are interconvertible, but the total amount of energy must not be conserved.

5.Consider an isolated system moving through empty space. The system consists of objects that interact with each other and can change location with respect to one another. Which of the following quantities can change in time? 选项：A:Both the angular momentum and linear momentum of the system. B:Neither the angular momentum nor linear momentum of the system. C:The angular momentum of the system. D:The linear momentum of the system.

6.质点系的动量定理，说的是___The Momentum Theorem for Particle Systems says___选项： A:质点系合外力的冲量，等于质点系动量的增量；The Momentum of Particle System is equal to the momentum increment of particle system;; B:质点系合外力的冲量，等于质点系动能的增量；The Impulse of particle system is equal to the increment of Kinetic Energy of particle system;; C:质点系合外力的冲量，等于质点系势能的增量；The Impulse of the particle system is equal to the increment of the Potential Energy of the particle system;; D:质点系合外力的冲量，等于质点系机械能的增量；The Impulse of particle system combined with external force is equal to the increment of Mechanical Energy of particle system;

7.A block is projected with speed v across a horizontal surface and slides to a stop due to friction. The same block is then projected with the same speed v up an incline where is slides to a stop due to friction. In which case did the total mechanical energy of the block decrease the least?选项： A:This problem cannot be solved since it was not indicated whether the horizontal surface and the incline both had the same coefficient of kinetic friction.; B:The case on the horizontal surface had the least decrease in total mechanical energy.; C:The case on the inclined surface had the least decrease in total mechanical energy.; D:In both cases the decrease in mechanical energy was the same.; E:None of the others.

8.10. A block is projected with speed v across a horizontal surface and slides to a stop due to friction. The same block is then projected with the same speed v up an incline where is slides to a stop due to friction. In which case did the total mechanical energy of the block decrease the least?选项： A:This problem cannot be solved since it was not indicated whether the horizontal surface and the incline both had the same coefficient of kinetic friction.; B:The case on the horizontal surface had the least decrease in total mechanical energy.; C:The case on the inclined surface had the least decrease in total mechanical energy.; D:In both cases the decrease in mechanical energy was the same.; E:None of the others.

9.Which statement best reflects the first law of thermodynamics 选项： A、Energy can change forms, but it cannot disappear. B、If a machine slows an object, energy will be conserved. C、The amount of energy in a system tends to increase over time. D、Nuclear energy must be regulated by international law.

10.Two blocks of different masses are pressed together on a horizontal frictionless surface with a compressed spring between them. They are not attached to the spring. After they are released and have both moved free of the spring: 选项： A:The lighter block will have more kinetic energy than the heavier one.; B:The heavier block will have more kinetic energy than the lighter one.; C:The two blocks will have the same amount of kinetic energy; D:Both will have the same speed

11.A block is projected with speed v across a horizontal surface and slides to a stop due to friction. The same block is then projected with the same speed v up an incline where is slides to a stop due to friction. In which case did the total mechanical energy of the block decrease the least?选项： A:This problem cannot be solved since it was not indicated whether the horizontal surface and the incline both had the same coefficient of kinetic friction.; B:The case on the horizontal surface had the least decrease in total mechanical energy.; C:The case on the inclined surface had the least decrease in total mechanical energy.; D:None of the others.

12.Einstein’s theory of relativity is based in part on which one of the following postulates? 选项： A、mass and energy are equivalent B、space and time are absolutes C、energy is conserved only in elastic collisions D、speed of light in a vacuum is same for all observers regardless of source velocity

13.(单选题)The thermal energy produced by an internal combustion engine is transformed into __. 选项： A:Combustion B:Internal C:External D:Mechanical

14.The payoff phase of glycolysis includes the energy-conserving phosphorylation steps in which some of the chemical energy of the glucose molecule is conserved in the form of ATP and NADH.

15.The requirement that energy （） conserved must be satisfied. [A] would be ; [B] should be; [C] will be; [D] is

16.When we pull a mass attached to horizontal spring on a frictionless surface and hold the mass at some position coordinate x, the force of the spring on m is equal in magnitude and opposite in direction to the force we exert on m. Are these forces a Newton’s third law force pair?选项： A:正确; B:错误

17.Which of the following statements does not describe the first law of thermodynamics. ( ) 选项： A、The quantity of energy is conserved during energy transformation from thermal energy to other forms of energy. B、To get work, thermal energy or other energy must be consumed. C、The efficiency of the heat engine may be greater than 1. D、The first kind of perpetual motion machine is impossible to be produced.

18.Wind power plant energy chain: ( ) -- Mechanical energy--electrical energy

19.The Impossibility of Rapid Energy Transitions A)Politicians are fond of promising rapid energy transitions.Whether it is a transition from imported to domestic oil or from coal-powered electricity production to natural-gas power plants,politicians love to talk big.Unfortunately for them (and often the taxpayers),our energy systems are a bit like an aircraft carrier:they are unbelievably expensive ,they are built to last for a very long time ,they have a huge amount of inertia (meaning it takes a lot of energy to set them moving),and they have a lot of momentum once they are set in motion.No matter how hard you try,you can ’t turn something that large on a d i me (10美分硬币),or even a few thousand dimes.B)In physics,moving objects have two characteristics relevant to understanding the dynamics of energy systems :inertia and momentum.Inertia is the resistance of objects to efforts to change their state of motion.If you try to push a bo uld er (大圆石),it pushes you back.Once you have started the boulder rolling,it develops momentum,which is defined by its mass and velocity.Momentum is said to be “conserved ,”that is ,once you build it up ,it has to go somewhere.So a heavy object ,like a football player moving at a high speed,has a lot of momentum —that is,once he is moving,it is hard to change his state of motion.If you want to change his course,you have only a few choices :you can stop him,transferring (possibly painfully)some of his kinetic energy (动能)to your own body,or you can approach alongside and slowly apply pressure to gradually alter his course.C)But there are other kinds of momentum as well.After all,we don ’t speak only of objects or people as having momentum ;we speak of entire systems having momentum.Whether it’s a sports team or a presidential campaign,everybody relishes having the big momentum,because it makes them harder to stop or change direction.D)One kind of momentum is technological momentum.When a technology is deployed,its impacts reach far beyond itself.Consider the incandescent (白炽灯的)bulb ,an object currently hated by many environmentalists and energy-efficiency advocates.The incandescent light bulb,invented by Thomas Edison,which came to be the symbol of inspiration,has been developed into hundreds,if not thousands,of forms.Today,a visit to a lighting store reveals a stunning array of choices.There are standard-shaped bulbs,flame-shaped bulbs,colored globe-shaped bulbs,and more.It is quite easy,with all that choice,to change a light bulb.E)But the momentum of incandescent lighting does not stop there.All of those specialized bulbs led to the building of specialized light fixtures,from the desk lamp you study by,to the ugly but beloved hand-painted Chinese lamp you inherited from your grandmother,to the ceiling fixture in your closet,to the light in your oven or refrigerator,and to the light that the dentist points at you.It is easy to change a light bulb,sure,but it is harder to change the bulb and its fixture.F)And there is more to the story,because not only are the devices that house incandescent bulbs shaped to their underlying characteristics,but rooms and entire buildings have been designed in accordance with how incandescent lighting reflects off walls and windows.G)As lighting expert Howard Brandston points out,“Generally,there are no bad light sources,only bad applications.”There are some very commendable characteristics of the CFL[compact fluorescent (焚光的)light bulb],yet the selection of any light source remains inseparable from the luminaire (照明装置)that houses it ,along with the space in which both are installed ,and lighting requirements that need to be satisfied.The lamp,the fixture,and the room,all three must work in concert for the true benefits of end-users.If the CFLshould be used for lighting a particular space,or an object within that space,the fixture must be designed to work with that lamp,and that fixture with the room.It is a symbiotic (共生的)relationship.ACFLcannot be simply installed in an incandescent fixture and then expected to produce a visual appearance that is more than washed out,foggy,and dim.The whole fixture must be replaced —light source and luminaire —and this is never an inexpensive proposition.H)And Brandston knows a thing or two about lighting,being the man who illuminated the Statue of Liberty.I)Another type of momentum we have to think about when planning for changes in our energy systems is labor-pool momentum.It is one thing to say that we are going to shift 30percent of our electricity supply from,say,coal to nuclear power in 20years.But it is another thing to have a supply of trained talent that could let you carry out this promise.That is because the engineers,designers,regulators,operators,and all of the other skilled people needed for the new energy industry are specialists who have to be trained first (or retrained,if they are the ones being laid off in some related industry),and education,like any other complicated endeavor,takes time.And not only do our prospective new energy workers have to be trained,they have to be trained in the right sequence.One needs the designers,and perhaps the regulators,before the builders and operators,and each group of workers in training has to know there is work waiting beyond graduation.In some cases,colleges and universities might have to change their training programs,adding another layer of difficulty.J)By far the biggest type of momentum that comes into play when it comes to changing our energy systems is economic momentum.The major components of our energy systems,such as fuel production,refining,electrical generation and distribution,are costly installations that have lengthy life spans.They have to operate for long periods of time before the costs of development have been recovered.When investors put up money to build,say,a nuclear power plant,they expect to earn that money back over the planned life of the plant,which is typically between 40and 60years.Some coal power plants in the United States have operated for more than 70years!The oldest continuously operated commercial hydro-electric plant in the United States is on New York ’s Hudson River,and it went into commercial service in 1898.K)As Vaclav Smil points out,“All the forecasts,plans ,and anticipations cited above have failed so miserably because their authors and promoters thought the transitions they hoped to implement would proceed unlike all previous energy transitions,and that their progress could be accelerated in an unprecedented manner.”L)When you hear people speaking of making a rapid transition toward any type of energy,whether it is a switch from coal to nuclear power,or a switch from gasoline-powered cars to electric cars,or even a switch from an incandescent to a fluorescent light,understanding energy system inertia and momentum can help you decide whether their plans are feasible.注意:此部分试题请在答题卡2上作答.46.Not only moving objects and people but all systems have momentum.47.Changing the current energy system requires the systematic training of professionals and skilled labor.48.Changing a light bulb is easier than changing the fixture housing it.49.Efforts to accelerate the current energy transitions didn ’t succeed as expected,50.To change the light source is costly because you have to change the whole fixture.51.Energy systems,like an aircraft carrier set in motion,have huge momentum.52.The problem with lighting ,if it arises,often doesn’t lie in light sources but in their applications.53.The biggest obstacle to energy transition is that the present energy system is too expensive to replace.54.The application of a technology can impact areas beyond itself.55.Physical characteristics of moving objects help explain the dynamics of energy systems

20.1. If an electrical machine can convert mechanical energy into electrical energy, we call it a ( )选项： A: motor ; B: generator; C: magnet; D: razor

21.Which of the following are the structural features of prokaryotic promoters( ) 选项： A、The starting point is usually a purine B、At 10 bp upstream of the starting point, there is a conserved region of about 6 bp, called the -10 region C、 35 bp upstream of the starting point, there is a conserved region of about 6 bp, called -35 region. D、The distance between two conserved regions is not important, but the sequence is critical.