Упражнения

I. Переведите следующие предложения:

1. Atomic nuclei can interact with neutrons, electrons, and gamma radiation. 2. As we should infer from the vigour with which its constituents combine, water is a very stable substance. 3. The current can flow through a wire only when the circuit is closed. 4. The magnitude of electrical current may vary from a minute amount to a very large quantity. 5. In the ammeter the current which is to be measured flows between terminals A and B. 6. Speaking about the structure of the atom one should remember that the proton is smaller but heavier than the electron. 7. Only very little current should flow through the voltmeter to operate it and its mechanism must be very delicate and fine. 8. To tear away from the liquid the molecule which leaves it should have a large amount of kinetic energy. 9. Elastic limit is the point beyond which one should not attempt deforming the body if it is to return to its original condition. 10. The convocation of international scientific conferences, which are to be attended by scientists from different countries and belonging to different schools, can undoubtedly promote the development of science. 11. The investment in an atomic reactor must be high, but the running cost is so low that something like a large tanker can be run as cheaply on atomic energy as on conventional fuel. 12. Working with picric acid one must remember of its explosive nature. 13. Our scientists had to solve the problem of controlling chain reactions. 14. The nature of the raw material must be taken into consideration in the selection of a method of its analysis. 15. One can obtain better results if the solution is slightly heated. 16. A voltmeter may be connected between any two points whose voltage difference is to be measured. 17. You ought to know the properties of the ingredients. 18. There must be a greater number of turns of wire on the field magnets to produce a magnetic field of adequate strength. 19. If "water gas" is to be used as a source of pure hydrogen, carbon monoxide must be removed. 20. One must remember that any reaction is theoretically reversible. 21. If we are to convert a gas into a liquid, we must increase the attraction of the molecules for one another. 22. The unit of heat should not be confused with the degree of temperature. 23. This explosive may be either a liquid or a solid.

II. Переведите текст, обращая внимание на модальности:

EQUILIBRIUM

With what can we associate the word "equilibrium"? We ought to know that the term applies equally well to a motor-car moving along a straight road at a constant speed. From a scientific point of view an object can be in equilibrium not only when it is standing motionless, but also when it is moving in a straight line at constant speed. On the other hand it would not be in equilibrium if it were increasing speed or slowing down or provided it were going around a corner.

Evidently, when there are no forces pulling or pushing a body, that body must always be in equilibrium. However, objects with forces acting on them may also be in equilibrium. But, then, the forces must balance; that is, their vector sum is to equal zero. Thus, in the case of the speeding automobile there are forces acting, but they balance each other in pairs. The pull of gravity downward is counteracted by the push of the road upward. The driving force supplied by the motor is balanced by air resistance and other frictional forces. However, as the driving force supplied by the motor is greater than the frictional resistance, the car is accelerated.

But sometimes an object may not be in equilibrium even though the vector sum of all the forces is zero. It may have a tendency to rotate unless all the forces are applied at a single point, or unless the tendency to rotate in one direction balances the tendency to rotate in the opposite.

Thus the second condition for equilibrium is that the tendency to rotate should be zero. There are always two requirements for equilibrium: first, the vector sum of all the forces acting on a body should be zero; and, second, there must be no tendency to rotate, that is, the tendency to rotate the body in one direction must be balanced by the tendency to rotate it in the opposite direction.

We have to point out the importance of equilibrium in any engineering design and construction. For example, if a house is to stand, each of its parts must evidently be in equilibrium.