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 19th 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?

Exercises

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

Encounter:

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.

impart

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.

eliminate

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:

recognize

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 emergencies that may occur during flight.

arrive

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.