Установите безопасный браузер
Grammar: Elliptic Sentences
Text 20 A
Primary cosmic rays are submicroscopic particles that travel in space outside the earth’s atmosphere at speeds nearly equal to that of light. Some of them happen to approach the earth and enter the atmosphere.
High in the atmosphere, most of the primary cosmic rays collide violently with the atoms they encounter in the air, in which case they impart their energies to the fragments resulting from the collision. In effect, these fragments or secondary rays are what we observe at lower levels. Like the primaries they too collide with atoms in the air, or eventually with atoms in the earth, until ultimately the energy is all transformed into heat. The term cosmic rays is used to refer both to the primary and secondary rays.
Although an ancient phenomenon, cosmic rays because of their small effects went unrecognized until the end of the last century and the beginning of the present century. The total energy of all cosmic rays arriving in the atmosphere per unit time is only about 10 microwatts per square meter, roughly equal to the energy in starlight and a 100,000,000 times less than the radiant en ergy from the sun. Therefore, cosmic rays do not affect life on the earth appreciably in any direct, physical way.
The discovery of the existence of cosmic radiation was a consequence of certain experiments undertaken on the conductivity of gases. It was be lieved, on theoretical grounds, that a gas should be non-conducting in the absence of radiation, provided that the potential gradient across it was not so high that sparking could take place. Curiously enough, experiments undertaken to test this hypothesi s showed that a sample of air in a closed vessel always exhibited a small electrical conductivity in spite of every precaution to eliminate radiation, and prevent leakage along the insulators. The conductivity was observed to increase in proportion to the p ressure of the enclosed air, and to be diminished by surrounding the vessel with thick shields; therefore, it seemed to be due to some kind of radiation continually entering the vessel through the walls. If so, this was a more penetrating radiation than h ad ever been known before.
Various suggestions were advanced to explain this phenomenon, among them residual radioactivity of the shielding materials, and spontaneous ionization due to the thermal motion of the gas molecules.
That these explanations were no t sufficient to account for the observed phenomena was shown by the experiments of some scientists who, in the years immediately prior to 1914, sent ionization chambers up with balloons, and measured the variation of the conductivity of the contained gas a s a function of altitude. They were able to show that conductivity, and hence the ionization produced in the gas, somewhat decreased up to an altitude of about 2,000 feet above sea-level, indicating sources on the earth, and thereafter increased steadily up to the highest altitude which their balloons reached (30,000 feet), at which altitude it was many times greater than at sea-level. From this experimental result it was clear that, whatever the source, the whole of the residual ionization observed at sea- level could not be attributed to the radioactivity of the earth, nor can it be a property of the gas with which the ionization chamber is filled. That the immediate source of the radiation is not the sun is a consequence of the fact that ionization was th e same, whether day or night, and was therefore not due to rays coming directly from the sun.
Although the above conclusions were confirmed by a number of physicists in the years immediately prior to the outbreak of the first world war, it was not until 1926 that the existence of the cosmic radiation was generally accepted.
The distinctive feature of cosmic rays is a unique concentration of energy in single elementary particles. Though apparently similar in substance (mainly protons or nuclei of hydrogen) to the rays that cause aurora borealis, primary cosmic rays have individual energies about a million times greater, and penetrate far into the atmosphere and occasionally deep into the earth. Whereas the average quantum energy in starlight is merely 2 ev, th e average energy of single particles in the primary cosmic radiation is 1010 times greater, or about 20 BeV.
Such particles are not deflected by the electric forces that normally keep atoms and particularly the nuclei of atoms apart; they can penetrate thr ough the middle of any nucleus and cause it to disintegrate and they can create out of their kinetic energies new types of unstable particles which otherwise would not exist naturally on the earth. The cosmic rays do not obey Newton’s laws of mechanics as do slower-moving bodies, but provide extreme examples requiring application of the principles of relativity.
аurora borealis – полярне сяйво
a BeV is equal to 1,000,000 electron volts
Answer the questions:
1.What are primary cosmic rays and where can they be found?
2.What do we call secondary rays?
3.Why were cosmic rays unrecognized until the end of the last century?
4.What was the discovery of the existence of cosmic radiation connected with?
5.What was clear from the experimental result?
6.When was the existence of cosmic radiation generally accepted?
7.What is the distinctive feature of cosmic rays?
I. Translate the following words paying attention to the prefixes.
demobilize, decode, deform, demagnetize, demilitarize, foresee, foretell, forecast.
II. Translate the sentences paying attention to the verbs in bold type
1. Once a solid propellant motor is ignited, it is difficult to turn it off, a limitation not encountered in the liquid propellant engine.
2. When radiant energy encounters a body or matter, part of the energy is stopped or absorbed by the matter.
3. An object becomes weightless when it is free to move through space without encountering resistance.
4. The final stage of this multiple-rocket will impart roughly fifty per cent of the required velocity to the satellite itself.
5. In the case of a rocket, the greatest possible quantity of thermal energy must be imparted to the matter ejected.
6. Our only interest in the jet forces concerns the accelerations, both linear and angular, that they impart to the rocket.
7. In order to eliminate the drag of the landing gear during the flight, the wheels are usually retracted into the body of wings.
8. In the principle of momentum the internal forces are eliminated; in the principle of energy they are not eliminated, except in the special case where they do no work and so contribute nothing to weight.
III. Translate the sentences paying attention to the adverbs: finally, ultimately, and eventually
1. Table II shows the complete series of radioactive elements, from uranium through radium and radon finally to lead which is not radioactive.
2. Heat produced by a radioisotope power system must eventually be radiated from the vehicle.
3. Some specialists believe that we shall ultimately have to depend on the radiant energy that we receive directly from the Sun.
4. Mendeleyev left blank spaces in his table predicting that eventually the missing elements would be found and described their properties.
IV. Translate the sentences paying attention to the meanings of the verbs in bold type
1. That some force is necessary to hold the planets in their elliptical orbits had been recognized before Newton.
2. That kinetic energy could be turned into potential energy was recognized in the early days of mechanics.
3. Radar has been defined as the art of detecting by means of radio echoes the presence of objects, determining their direction and range and recognizing their character.
4. The technician of an airplane must have sufficient knowledge of the system to enable him to recognize and meet the electrical emergenc ies that may occur during flight.
5. The delegation arrived just in time to take part in the conference.
6. In general celestial mechanics arrives at its results by making use of a very far-reaching simplification.
V. Translate the sentences. Mind the difference in the meanings of the verbs to effect and to affect.
1. The decrease of density of the air affects the power of the engine.
2. Some mechanism is needed to inject the propellant into combustion chamber, and this is effected by the pressurization of the propellant tanks.
3. The intensity of the cosmic ray radiation is greatly affected by solar activity.
4. Protons, being positively charged particles, can be affected by electric as well as magnetic fields.
5. Radioisotope thermionic systems are unaffected by space radiation.
VI. Translate the sentences paying attention to the words in bold type.
thereafter: після цього
therefrom: з цього
1. The high-velocity jet from a jet engine may be considered as a continuous recoil imparting force against the airplane in which the engine is installed, thereby producing thrust.
2. Scientists had to put forward various hypothesis to account for the movements of planets therewith.
3. A molecule is a complicated structure with atoms and electrons therein.
4. When the primary cosmic rays strike the air surrounding the earth, they collide with oxygen and nitrogen molecules in their paths, showers of secondary particles being produced thereafter.
5. We can study only a very small class of meteor orbits, and to draw therefrom conclusions about the whole assemblage of meteoric bodies in the solar system.
VII. Translate the sentences paying attention to the meanings of the adjective apparent.
1. In recent years the value of infra-red analytical methods has become apparent to industry.
2. If energy changes are followed backward in the past, it becomes apparent that almost all the energy available to us has come ultimately from a single source – the Sun.
3. Centrifugal force is only an apparent force, which arises because of the tendency of moving objects to travel in straight lines.
4. Apparent movements of the planets are explained as combinations of their actual motions around the Sun and our shift of position as the Earth moves.
VIII. Translate the sentences paying attention to the words of the same root.
1. On the occasions when the Moon passes directly before or behind the Earth, an eclipse occurs.
2. Today a motor-car engine will run thousand of miles without needing any attention to the engine apart from occasional oiling.
3. That water exists on Mars is indicated by the white polar caps and by occasional clouds, but its amount is very small.
4. Most comets are visible only telescopically, but occasionally one becomes visible to the unaided eye.
IX. Translate the sentences paying attention to the meanings of the preposition by
1. If the thrust generated by the jet engine is independent of the forward speed of the aircraft, we could convert the thrust to horsepower by multiplying the airspeed in miles per hour by the thrust and dividing the resultant product by 375.
2. By 1914 the existence of radioactivity and the fact that atoms of one kind of element could change into another by emission of alpha or beta rays was well known.
3. By Newton’s Second Law of motion, the product of a mass multiplied by its acceleration is equal to the unbalanced force causing the acceleration.
TEXT 20 B
EXPLORING OUR SUN
Give a summary of the text.
(A.Clark. Profiles of the Future)
How close to the Sun could a man-carrying ship approach in safety? The answer to this question depends upon the skill of the refrigeration experts; my guess is that five million miles is an attainable distance even with a crew-carrying vehicle.
There is one useful trick we may employ to get quite close to the Sun in (almost) perfect safety. This is to use some asteroid or comet as a sunshade, and the best choice known at the moment is the little flying mountain named Icarus.
This minor planet travels on an orbit that every thirteen months brings it within a mere 17 million miles of the Sun.
Occasionally, it also passes quite close to Earth; it was within 4 million miles of us in 1968.
Though small in diameter (approximately one or two miles), Icarus casts a cone of shadow into space, and in the cold shelter of that shadow, a ship could travel safely around the Sun.
Small though it is, this minor planet must weigh about 10 billion tons.
There may be other asteroids that go even closer to the Sun, if there are not, we may undoubtedly one day make them do so by a nudge at the right point in the orbit.
It is interesting to consider how long the travel would take. Being a rather small star, the Sun is only three million miles in circumference. A satellite just outside its atmosphere would move about a million miles an hour, so would circle it every three hours.
Magneto-hydrodynamics is concerned with the handling of very hot gases in magnetic fields. Already it has enabled us to produce temperatures of tens of millions of degrees in the laboratory, and ultimately it may lead us to the limitless power from hydrogen fusion.
I suggest that, when we have acquired some real mastery of this infant science, it will also give us magnetic and electric shields that can provide far more effective protection against both temperature and pressure that can be obtained from any walls of metal.
guess — припущення
cast a cone of shadow — відкидати тінь у вигляді конуса
nudge — поштовх
circumference — коло