Home Random Page


CATEGORIES:

BiologyChemistryConstructionCultureEcologyEconomyElectronicsFinanceGeographyHistoryInformaticsLawMathematicsMechanicsMedicineOtherPedagogyPhilosophyPhysicsPolicyPsychologySociologySportTourism






Unit One PHYSICS AS A BRANCH OF SCIENCE

Text 1 . What is Physics?

Parti

Physics is the scientific study of matter and energy and how they interact with each other.

This energy can take the form of motion, light, electricity, radiation, gravity: just about anything, honestly. Physics deals with matter on scales ranging from subatomic particles (i.e. the particles that make up the atom and the particles that make up those particles) to stars and even entire galaxies.

How Physics Works

As an experimental science, physics utilizes the scientific method to formulate and test hypotheses that are based on observation of the natural world. The goal of physics is to use the results of these experiments to formulate scientific laws, usually expressed in the language of mathematics, which can then be used to predict other phenomena.

The Role of Physics in Science ^

In a broader sense, physics can be seen as the most fundamental of the natural sciences. Chemistry, for example, can be viewed as a complex application of physics, as it focuses on the interaction of energy and matter in chemical systems. We also know that biology is, at its heart, an application of chemical properties in living things, which means that it is also, ultimately, ruled by the physical laws.

Because physics covers so much area, it is divided into several specific fields of study, such as:

> Acoustics - the study of sound and sound waves

> Astronomy - the study of space

> Cosmology-the study of universe

> Atomic Physics - the study of atoms, specifically the electron properties ofthe atom

> Electromagnetism - the study of electrical and magnetic fields, which are two aspects of the same phenomenon

> Electronics - the study of the flow of electrons, generally in a circuit

> Geophysics - the study of the physical properties of the Earth

> Laser Physics-the study ofthe physical properties of lasers

> Mechanics - the study of the motion of bodies in a frame of reference

> Molecular Physics - the study of physical properties of molecules

> Nanotechnology - the science of building circuits and machines from single molecules and atoms

> Nuclear Physics - the study of the physical properties of the atomic nucleus

> Optics - the study of the physical properties of light

> Thermodynamics - the physics of heat.


Branch of physics Object of study
  sound and sound waves
  universe
  space
  electrical and magnetic field
  electron properties of the atom
  flow of electrons
  motion
  properties of molecules
  properties of light
  heat
II. Summarize the text using the table.

 

Text 2 What is physics?

Part II |

Physics is often described as the study of matter and energy. It is concerned with how matter and energy relate to each other, and how they affect each other oyer, jtime and through space. Physicists ask the fundamental questions how did the universe begin? how and of what is it made? how does it change? what rales govern^ ^ its behavior?



Physicists may be roughly divided into two camps: experimental physicists and theoretical physicists. Experimental physicists design and run, careful ^investigations on a broad range of phenomena in nature, often under conditions which are atypical of our everyday lives. They may, for exam^^lnvestigate what happens to the electrical properties of materials at temperatures very near absolute zero (460 degrees Fahrenheit) or measure the characteristics of energy emitted by very hot gases. Theoretical physicists propose and develop models and theories to explain mathematically the results of experimental observations. Experiment and theory therefore have a broad overlap. Accordingly, an experimental physicist remains keenly aware of the'ciSTeflffReoretical work in his or her field, while the theoretical physicist must know the experimenter's results and the context in which the results need be interpreted.

It is also useful to distinguish classical physics and modern physics. Classical physics has its origins approximately four hundred years ago in the studies of Galileo and Newton on mechanics, and similarly, in the work of Ampere, Faraday, Maxwell and Oersted one hundred fifty years ago in the fields of electricity and magnetism.

This physics handles objects which are neither too large nor too small, which move at relatively slow speeds (at least compared to the speed of light: 186,000 miles per second!). 15

The emergence of modem physics at the beginning of the twentieth century was marked by three achievements. The first, in 1905, was Einstein's brilliant model

|qr -


of light as a stream of particles (photons). The second, which followed a few months later, was his revolutionary theory of relativity which described objects moving at speeds close to the speed of light. The thirdLftreakthrough came in 1910 with Rutherford's discovery of the nucleus of the atomRuffierford's work was followed by Bohr's model of the atom, which in turn stimulated the work of de Broglie, Heisenberg, Schroedinger, Born, Pauli, Dirac and others on the quantum theory. The avalancheof exciting discoveries in modem physics continues today.

4" Given these distinctions within the field of physics experimental and theoretical, classical and modem it is useful to further subdivide physics into various disciplines, including astrophysics, atomic and molecular physics, biophysics, solid state physics, optical and laser physics, fluid and plasma physics, nuclear physics, and particle physics.

I. Find in the text English equivalents to the following words and word combinations:

, , , , , , , , , , ..., , , , . ^

II. Answer the questions below:

1. What is physics?

2. What does it study?

3. What are the fundamental questions concerned to?

4. What groups can the physicists be divided to?

5. What do the experimental physicists investigate?

6. What do the theoretical physicists develop?

7. What periods are distinguished in the history of physics?

8. When did the classical physics appear?

9. What does it deal with?

10. When did the modem physics appear?

11. Who developed the model of light?

12. Who invented the theory of relativity?

13. Who investigated the nucleus of the atom and developed the model of atom?

14. Who worked in the field of quantum theory?

15.What branches of physics do you know?

III. Comprehension check. Read the text in detail, say whether these statements are true or false. If they are false make your own true ones.

1. Physics deals with the study of matter and energy

2. Experimental physics develop experiments in atypical conditions.

3. Theoretical physics propose theories to explain the results of observations.

4. Modem physics was followed by classical physics.

5. Galileo and Newton represent modem physics.


6. Classical physics appeared in the 20-th century.

7. Einsteins model of light gave the beginning to classical physics.

8. Theory of relativity and discovery of the nucleus of the atom were connected with modem physics.

9. The goal of physics is to predict different phenomena.

10. Scientific method in physics helps to formulate hypotheses and to test them.

IV. Summarize the text using the key points given below:

1. Studying object of physics.

2. Camps of physicists.

3. From the history of physics.

Text 3

I. Read the text. Choose the title from the following:

1. From the History of Physics.

2. Materialists and Idealists.

3. Philosophical Basis of Physics.

Physics as a science appeared only due to the fact that its creators, Galileo, Newton, Hooke, Huygens, Euler, Laplace, Faraday, Maxwell and many other researchers adhered to some original philosophical principles and rules for doing science.

What are the philosophical principles, on which physics is based? At first, it is the independence of existence of nature from our consciousness; matter is self- sufficient and its laws of motion depend neither on God, nor on the observer. Secondly, researches into nature should be based:

- on direct contemplation and observation;

- on precise facts;

- on experiments,

- on a faith in the cognizance of nature;

- on a faith that nothing is present in space except moving matter. All laws of nature, all natural phenomena, all facts, connected with the motion, are causal, and these reasons ought to be possible to find.

Based on such a (materialistic) philosophy, everyone of the famous researchers (except for the relativists, who deviated from these principles) created or supplemented the rules for doing science. Three of the foremost of these (not counting the Ancient Greek and the Middle Ages scientists) were Kant, Huygens and Newton.

Newton grounded his postulates about the invariance of space, time, and mass by direct contemplation of nature instead of by the invention of hypotheses.

III. Summarize the text using the table.

 

Text 4 Thermodynamics

Thermodynamics means the dynamics of heat - that is the production, flow, and conversion of heat into work. We use heat energy, either directly or indirectly, to do most of the work that is done in everyday life. The operation of heat engines, such as intemal-combustion engines, and of refrigerators is based on the laws of thermodynamics.

TTie first law of thermodynamics is the principle of energy conservation applied to thermodynamic process. For example, lets consider a balloon heating.^As energy is added to the system (the balloon and the air inside), the temperature increases and the balloon expands^ The temperature of the air inside the balloon increases because some of the heat goes into the internal energy of the air. Some of the energy also goes into doing the work of expanding the balloon.

Mathematical statement of the first law of thermodynamics:

Heat added to a closed system goes into the internal energy of the system and/or doing work.

In the process the engine uses some of the input energy to do work, heat in = work + heat out or

work = heat in - heat out __

Normally^a heat engine operates in a cycle for continuous output. ^

In a cyclical heat engine the system comes back to its original state. Thus the temperature and internal energy of the system are unchanged.

The conversion of heat energy into work is expressed in terms of thermal efficiency. Similar to mechanical efficiency, it is a ratio of the work output and the energy input. That is,

work -output

thermal efficiency =---------------------- x 100%

heat input

The efficiency of an automobile is approximately 15%. It means that 85% of the energy from fuel combustion is wasted or goes into something which has nothing to do with moving the car. For example, running a tape player.

The second law of thermodynamics can be stated as follows:

No heat engine operating in a cycle can convert heat energy completely

into work.

Another way of saying this is that no heat engine operating in a cycle can have 100 percent efficiency. ,

heat engine must lose some heatjft can be shown that the maximum or ideal efficiency is exclusively determined by the high and low temperatures of the reservoirs.

The actual efficiency of a heat engine will always be less than its ideal efficiency. The ideal efficiency sets an upper limit, but this limit can never be achieved.

Notice that the second law forbids a cold reservoir of T^^OK. If absolute zero could be used, then we could have an ideal efficiency of 100 percent, which would violate the second law. Actually a temperature of absolute zero cannot be attained.

That is, thermodynamically, it is impossible to obtain a temperature of . absolute zero. This result is sometimes called the third law of thermodynamics. ^[Scientists have tried to reach absolute zero and have come within one-millionth of a degree ,"|I owever, the third law has still never been violated experimentally.

L Comprehension check. Read the text and answer the questions.

1. What do the first law and the second law of thermodynamics tell you?

2. Distinguish between thermal efficiency and ideal efficiency.

3. In what way does the heat engine operate?

4. What does the third law of thermodynamics tell you?

5. Is it possible to construct an engine which will work in a cycle and produce continuous work, or kinetic energy, from nothing?

II. Cover the text and choose the best ending for each sentence:

1. The operation of heat engines (e.g. intemal-combustion engine) is dealt with 0

a) nuclear physics

b) mechanics

c) thermodynamics

2. The first law of thermodynamics is simply the principle of conservation of '

a) matter

b) field

c) energy y

3. Heat added to a closed system goes into the ' ■

a) external energy of the system

b) internal energy of the system


4. Thermal efficiency is ratio of Q

a) the work input and the energy output

b) the work input and the energy input

5. Heat engine operating in cycle '■

a) can convert heat energy completely into work

b) cant convert heat energy completely into work

III. The following statements are false. Change one word or phrase in each statement to make it true.

1. The laws of thermodynamics are important because they give relations between heat energy work and distance.

2. As energy is added to the system (the balloon and the air inside) the temperature increases and the balloon contracts.

3. A heat engine is a device that converts heat into power.

4. A heat engine operates in cycle for continuous energy input.

5. The second law of thermodynamics can be stated in one way.

6. Scientists have tried to reach absolute zero and have come ^rithin one- hundredth of degree.


Date: 2015-02-16; view: 679


<== previous page | next page ==>
Unit 2 Computer Architecture | Text 5 Quantum Physics
doclecture.net - lectures - 2014-2018 year. Copyright infringement or personal data (0.005 sec.)