Albert Einstein (1879–1955) developed the theory of relativity and, along with many other scientists, developed quantum theory. This theory does not have the constraints present in classical physics. All of the situations we consider in this chapter, and all those preceding the introduction of relativity in Special Relativity, are in the realm of classical physics.
Physics is a science about the energy in the universe, in all its various forms. Here on Earth, the source of our energy, directly or indirectly, is the sun. Solar power, wind power, hydroelectric power, fossil fuels, we can eventually trace the origin of all energy on our planet back to our sun. So where do we start in our study of the universe?
Theoretically, we could start by investigating any of these types of energy. In reality, however, by starting with energy of motion (kinetic energy), we can develop a set of analytical problem solving skills from basic principles that will serve us well as we expand into our study of other types of energy.
For an object to have kinetic energy, it must be moving. Specifically:
If kinetic energy is energy of motion, and energy is the ability or capacity to do work (moving an object), then we can think of kinetic energy as the ability or capacity of a moving object to move another object.
But what does it mean to be in motion? A moving object has a varying position… its location changes as a function of time. So to understand kinetic energy, we'll need to better understand position and how position changes. This will lead us into our first major unit, kinematics, from the Greek word kinein, meaning to move. Formally, kinematics is the branch of physics dealing with the description of an object's motion, leaving the study of the «why» of motion to our next major topic, dynamics.
VI. Are the sentences true (T), false (F) or not given (NG)
1. Physics is a science studying kinetic energy.
2. The Sun is the source of our energy.
3. Due to the sun we can get solar power, wind power, hydroelectric power, and fossil fuels.
4. Energy that we get from the sun is expensive.
5. The object must not move to have kinetic energy.
6. A moving object’s location changes as a function of time.
7. The word kinematics is from the Greek word kinein, meaning to jump.
8. Kinematics is a branch of mathematics.
VII. Answer the questions on the text
1. What do you understand by Physics?
2. What sources of energy do you know?
3. What is the origin of the word ‘kinematics?
4. An astronaut drops a hammer from 2.0 meters above the surface of the Moon. If the acceleration due to gravity on the Moon is 1.62 meters per second2, how long will it take for the hammer to fall to the Moon’s surface?
UNIT 6
Vocabulary
free a. – свободный; ~ of charge бесплатный;
to fall (fell, fallen) v. – падать; понижаться; n. падение;
to believe v. – верить, полагать, считать;
due to prep. – из-за, благодаря, вследствие;
to drop v. – бросать, оставлять;
– the idea перестать думать,
отказаться от мысли; n капля;
simultaneously adv. – одновременно;
to crumple v. – мять (ся); комкать морщиться съеживаться;
to conclude v. – 1) заключить; 2) прийти к выводу;
resistance n. – 1) сопротивление;
2) v. сопротивляться;
оказывать сопротивление;
to neglect v. – пренебрегать;
to execute v. – выполнять; executable a. – выполняемый;
strength n. – прочность; ~ of materials сопротивление материалов;
surface n. – 1) поверхность; 2) a. наружный;
to indicate v. – показывать;
I. Practice pronunciation of the following words:
massive ['masɪv] continuously ['kən,tɪnjʊəsli| ]
feather [ fɛðə] gravitation [ɡravɪteɪʃ(ə)n]
piece ['pi: s] strength [streŋθ]
tight [tʌɪt] analyze ['ænəlaɪz]
air [eə] local [ləʊk(ə)l]
purpose ['pə:pəs] affect [ə'fɛkt]
II. Read and translate the words having the same root correct – correction – corrective – correctly – corrector – incorrect; conclude – concluding; prediction – predict – predictable – predicted; affect – affected – affection – affective – affecting; perform – performance – performer – performing – performed; acceleration – accelerated – accelerating.
III. Fill in the gaps with the words below
1. The _________ of an object is the rate of change of its position with respect to a frame of reference and is a function of time.
2. ____________of metals decreases at low temperature.
3. Our planet belongs to planets of terrestrial group. It means that the Earth's _____________is firm.
4. Mechanical ____________ is defined by numerous testing machines.
5. If you ____________ a load, it will ___________ with high speed.
IV. Mind the explanation of the following terms
height – how far it is from the bottom to the top of somebody or something .
hypothesis – theory that you then test through study and experimentation.
experiment