V. Translate the following sentences. Pay attention to the infinitive constructions.

1. All bodies are known to possess weight.

2. Newton noticed the apple fall from thee tree.

3. The acceleration is said to be positive when the force is supplied by the motor to speed up the car.

4. The invention of this device is expected to produce a great increase in the production of the material.

5. At present we know heat to be a form of energy.

Speaking

VI. Discuss in the group.

1. Newton’s favorite study.

2. The theory of gravity.

9 Energy and its forms

Reading

I. Read the following words:

scientifically, weight, mechanism, height, hour, chemical, light, hydroelectric, quantity, electron, atom, molecule, substance, quantity, thermal, earth.

II. Read and translate the text

Scientifically speaking, energy is the capacity for doing work. When a body is capable of performing work, it possesses energy. It is quite clear that the more work a body can do, the more energy it possesses.

There are numerous forms of energy, such as: electrical, chemical, mechanical, heat energy and so on. In mechanics, there are two special kinds of energy, namely, kinetic energy and potential energy.

It is quite possible to transform one form of energy into another. Take a waterfall as an example: when water falls from a height, the energy is said to change from potential to kinetic. If there is a hydroelectric plant at the waterfall, the energy of the falling water is used to drive the turbines. The turbines are driven by the kinetic energy of the water. Since it is difficult to transfer mechanical energy over a great distance, it is used here to drive generators. These generators, in their turn, change mechanical energy into electric energy.

There are many forms of energy, but they can all be put into two categories: kinetic and potential. Kinetic energy is the energy of motion, while potential energy is that of position. The kinetic energy of an object is the energy that it possesses because of its speed. Any moving object is expected to perform work simply because it is moving, the quantity of energy depending on its mass and velocity. It has been found that the greater the mass and the velocity, the greater is the kinetic energy.

Forms of energy
Kinetic energy motion of waves, electrons, atoms, molecules, substances, and objects	Potential energy stored energy and the energy of position – gravitational energy
Electrical Energy is the movement of electrical charges. Electrical charges moving through a wire is called electricity. Lightning is another example of electrical energy.	Chemical energy is energy stored in the bonds of atoms and molecules. It is the energy that holds these particles together. Biomass, petroleum, natural gas are examples of stored chemical energy.
Radiant Energy is electromagnetic energy that travels in transverse waves. Light is one type of radiant energy. Solar energy is an example of radiant energy.	Stored Mechanical Energy is energy stored in objects by the application of a force. Compressed springs and stretched rubber bands are examples of stored mechanical energy.
Thermal Energy, or heat, is the internal energy in substances––the vibration and movement of the atoms and molecules within substances. Geothermal energy is an example of thermal energy.	Nuclear Energy is energy stored in the nucleus of an atom––the energy that holds the nucleus together.
Motion Energy is the movement of objects and substances from one place to another. Wind is an example of motion energy.	Gravitational Energy is the energy of position or place. A rock resting at the top of a hill contains gravitational potential energy.
Sound is the movement of energy through substances in longitudinal waves.