Unit 4 Theme:Thermal energy

Grammar: Gerund: Gerundial Constructions

Objectives: By the end of this unit, students should be able to use active vocabulary of this theme in different forms of speech exercises.Students should be better atdiscussing energy system. Students should know the rule of Gerundand fulfill grammar exercises.

Methodical instructions: This theme must be worked out during two lessons a week according to timetable.

Lexical material: Introduce and fix new vocabulary on theme “Thermal energy”.

Define thebasic energy system and its role in our country. Discuss in groups‘Thermal energy in our society’.

Grammar: Introduce and practice theGerund

Ex.1 Read the text and translate.

Thermal energy

Thermal energy is the part of the total internal energy of a thermodynamic system or sample of matter that results in the system temperature. The internal energy, also often called the thermodynamic energy, includes other forms of energy in a thermodynamic system in addition to thermal energy, namely forms of potential energy that do not influence temperature, such as the chemical energy stored in its molecular structure and electronic configuration, intermolecular interactions associated with phase changes that do not influence temperature (i.e., latent energy), and the nuclear binding energy that binds the sub-atomic particles of matter.

Microscopically, the thermal energy is partly the kinetic energy of a system’s constituent particles, which may be atoms, molecules, electrons, or particles in plasmas. It originates from the individually random, or disordered, motion of particles in a large ensemble. In ideal monatomic gases, thermal energy is entirely kinetic energy. In other substances in cases where some of thermal energy is stored in atomic vibration, this vibrational part of the thermal energy is stored equally partitioned between potential energy of atomic vibration, and kinetic energy of atomic vibration. Thermal energy is thus equally partitioned between all available quadratic degrees of freedom of the particles. As noted, these degrees of freedom may include pure translational motion in gases, in rotational states, and as potential and kinetic energy in normal modes of vibrations in intermolecular or crystal lattice vibrations. In general, due to quantum mechanical reasons, the availability of any such degrees of freedom is a function of the energy in the system, and therefore depends on the temperature (see heat capacity for discussion of this phenomena).

Macroscopically, the thermal energy of a system at a given temperature is related proportionally to its heat capacity.

Thermal energy is distinct from heat. Thermal energy is a state function, a property of a system, while heat, in the strict use in physics, is characteristic only of a process, i.e. it is absorbed or produced as an energy exchange, always as a result of a temperature difference. It is not a static property of matter. Matter does not contain heat, but rather thermal energy. Heat is thermal energy in the process of transfer or conversion across a boundary of one region of matter to another, as a result of a temperature difference. In engineering, the terms “heat” and “heat transfer” are thus used interchangeably, since heat is always understood to be in the process of transfer. The energy transferred by heat is called by other terms (such as thermal energy or latent energy) when this energy is no longer in net transfer, and has become static.

When two thermodynamic systems with different temperatures are brought into diathermic contact, they spontaneously exchange energy as heat, which is a transfer of thermal energy from the system of higher temperature to the colder system. Heat may cause work to be performed on a system, for example, in form of volume or pressure changes. This work may be used in heat engines to convert thermal energy into other forms of energy. In geothermal power plants it is used for the generation of electricity. When two systems have reached a thermodynamic equilibrium, they have attained the same temperature and the net exchange of thermal energy vanishes—heat ceases.

Ex.2 Topical vocabulary

Constituenta) to disappear suddenly or in a way that you can`t explain

Randomb) the amount that a container or space can hold

Absorbedc) one of the parts that forms something

Partitioned d) to change from one form, system or use to another

Capacity e) chosen by chance

Convert f) something that divides a room, office into two or more parts

Vanishesg) to take in and hold something (a liquid, heat)

Ex.3 Read and summarize the text