Вопрос № 256501 - Английский язык

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It may be assumed that a body consists of small particles or molecules, between which forces are acting. These molecular forces resist the change in the form of the body which external forces tend to produce. If such external forces are applied to the body, its particles are displaced and the mutual displacements continue until equilibrium is established between the external and internal forces. It is said in such a case that the body is in a state of deformation or strain. During deformation the external forces acting upon the body do work, and this work is transformed completely or partially into the potential energy of strain. An example of such an accumulation of potential energy in a strained body is the case of a watch spring. If the forces which produced the deformation of the body are now gradually diminished, the body returns wholly or partly to its original shape and during this reversed deformation the potential energy of strain, accumulated in the body, may be recovered in the form of external work.
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Molecular forces resist the change in the form of the body which external forces tend _________________.

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Everything happens because of energy. Without it there would be no life on Earth. Scientists classify energy into several different types, including chemical energy, light energy, and nuclear energy. Most types of energy can switch from one form to another. In a car, for example, gasoline provides chemical energy, which turns into mechanical energy, heat energy, and sound energy when the engine is started. All energy that comes from directly or indirectly from the Sun is known as radiant energy and makes up the electromagnetic spectrum.
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There exist many sources of energy in the world both potential and kinetic. One source consists in water falling from a high level such as an upland lake. Another source is wind or moving air. Others consist in tides in the sea, heat from subterranean sources and coal deposits and oil wells yielding mineral oil.
But all these sources and stores of energy are not equally useful to mankind. Moreover some stores of energy such as coal and oil can never be replaced by us when once used up. On the other hand stores of high level water are continually being replaced by rain and wind and tides will not, as far as we know, ever cease to exist. A very important matter is the conversion of energy from one form to another. The form most required by us is mechanical rotational energy.
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Stores of high level water are continually being replaced by rain and wind and tides will not ever ________________.

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Mechanical rotational energy is required to rotate shafts in a factory for driving various machines and also for driving the wheels of vehicles or automobiles or locomotives. The energy of water power is very unequally distributed, some countries such as Norway and Switzerland being rich in it and some such as England poor. England is rich in the potential energy of coal but has little or no oil wells.
Appliances for converting energy from one form to another are called engines. Thus a heat-engine is a machine for converting heat energy into mechanical energy of rotation by the combustion of coal or oil. A turbine or water engine can convert the kinetic energy of falling water into mechanical rotational energy.
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The energy of water power is ___________________.

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It may be assumed that a body consists of small particles or molecules, between which forces are acting. These molecular forces resist the change in the form of the body which external forces tend to produce. If such external forces are applied to the body, its particles are displaced and the mutual displacements continue until equilibrium is established between the external and internal forces. It is said in such a case that the body is in a state of deformation or strain. During deformation the external forces acting upon the body do work, and this work is transformed completely or partially into the potential energy of strain. An example of such an accumulation of potential energy in a strained body is the case of a watch spring. If the forces which produced the deformation of the body are now gradually diminished, the body returns wholly or partly to its original shape and during this reversed deformation the potential energy of strain, accumulated in the body, may be recovered in the form of external work.
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Molecular forces resist the change in the form of the body which external forces tend _________________.

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The property of bodies of returning, after unloading, to their initial form is called elasticity. It is said that the body is perfectly elastic if it recovers its original shape completely after unloading; it is partially elastic if the deformation, produced by the external forces, does not disappear completely after unloading. In the case of a perfectly elastic body, the work done by the external forces during deformation will be completely transformed into the potential energy of strain. In the case of a partially elastic body, part of the work done by the external forces during deformation will be dissipated in the form of heat which will be developed in the body during non-elastic deformation. Experiments show that such structural materials as steel, wood, and stone may be considered as perfectly elastic within certain limits.
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The body is perfectly elastic if it recovers its original shape completely _____________.