UNIT 7

 

I. Find out the words in the dictionary. Write them down and learn.

 

behaviour, intrinsic, to depend on, to define, gravity, to attract, friction, viscous force, resistance, downward force, upward force, strength, density, per unit volume, specific gravity, to be equal, to prevent, to be equal

 

II. Read the text. Use a dictionary, if necessary.

 

Text: “Statics”.

 

Statics is the branch of physics that deals with the behavior of bodies that are held stationary under the influence of a system of forces. The study of statics depends crucially on an understanding of the concept of force, which can be defined as an agent that is capable of altering the state of rest or motion of an object.

The most common force is that of gravity which on earth attracts everything downwards to its surface. Other forces include friction, which in some cases can act against another force to prevent movement, and the viscous force that acts against the force of gravity when a small object is dropped into, for example, a container of syrup.

The action of a force depends on the mass of the object on which it is exerted. Mass is defined as the resistance of an object to any change of its state of motion or rest by the action of a force. Mass is, therefore, a measure of the inertia of an object. The greater an object’s mass, the smaller is the acceleration, that a given force produces. The weight of an object is not, however, an unchanging intrinsic property. It is the downward force of an object resulting from the action of the force of gravity. So, although an object’s mass is the same everywhere, its weight depends on the strength of the gravitational field acting on it.

One of the major areas of study in statics is the behavior of objects in fluids (that is, in liquids and gases). Much of this work revolves around the concept of density, which is the mass of an object per unit volume. Another useful concept is that of specific gravity, or relative density. This property is given by the density of an object divided by the density of water.

An important law in the statics of fluids is Archimedes’ principle. It states that the upward force acting on an object immersed in a fluid is equal to the weight of fluid that is displaced. The value of the principle lies in providing a way of finding the specific gravity, and therefore the density of an object without measuring both its mass and volume. Legend tells of Archimedes applying the principle after being asked by the King of Syracuse to prove that a gold crown was indeed made of solid gold. The crown was intricately worked and finding its volume would have been extremely difficult. So Archimedes found its density by putting the crown and then an equal weight of pure gold in a bowl of water and measuring the amount of water displaced by each. He found that the crown displaced more water than the gold weight did. It meant that the crown had a greater volume and therefore consisted of a material of lower density than pure gold.

 

III. Form nouns from the following verbs by adding the suffixes - er, - or, - tion, - sion, - ty, - ance, etc. or not changing anything. Translate the nouns.

 

To depend on, to influence, to force, to understand, to define, to move, to attract, to act, to prevent, to resist, to change, to accelerate, to produce, to revolve, to divide, to displace, to measure, to provide.

 

IV. Practice the following speech patterns.

 

Pattern 1.  Statics deals with studying the behaviour of stationary bodies.

 

physics –  the properties of bodies

theoretical physics – the laws and principles

experimental physics – the experiments and observation

statics – the behaviour of stationary bodies

dynamics – the behaviour of bodies under the influence of forces

 

Pattern 2.  The study of statics depends on the concept of force.

 

the development of other sciences – the knowledge of physical phenomena  

the action of a force – the mass of the object

an object’s weight – the strength of the gravitational field

 

Pattern 3.  Mass is defined as the resistance of an object to any change.

 

force – an agent that can alter the state of rest or motion of an object

gravity – a force that on earth attracts everything downwards to its surface

friction – a force that can actagainst another force to present movement

 

V. Find the sentences that can’t be found in the text.

 

1. The study of statics depends crucially on an understanding of the concept of force.
2. The most common force is that of gravity, which on earth attracts everything downwards to its surface.
3. The moon’s gravitational fields, for example, is only one-sixth as powerful as the earth’s, and as a result the weight of an object on the moon is only one-sixth of its weight on earth.
4. One of the major areas of study in statics is the behaviour of objects in fluids.
5. If the mass is measured in kilograms and the unit of volume is the cubic meters, then density is measured in kilograms per cubic meter. 
6. An important law in the statics of fluids is Archimedes’ principle. 
7. The density of liquids is measured by hydrometers. 

 

VI. Find English equivalents in the text.

 

1. поведение тел ________________________________________________
2. под воздействием _____________________________________________
3. зависит от понимания _________________________________________
4. способен изменить состояние покоя или движения _________________
5. сила трения __________________________________________________
6. препятствовать движению ______________________________________
7. сила вязкости _________________________________________________
8. сопротивление ________________________________________________
9. сила, направленная вниз _______________________________________
10. напряжённость гравитационного поля ____________________________
11. текучие среды ________________________________________________
12. масса тела на единицу объёма ___________________________________
13. удельный вес _________________________________________________
14. плотность тела, делённая на плотность воды _______________________
15. сила, направленная вверх _______________________________________
16. обеспечить способ определения __________________________________

 

VII. Find Russian equivalents to the following expressions in the text.

 

1. branch of physics _____________________________________________
2. the concept of force ___________________________________________
3. bodies that are held stationary ___________________________________
4. can be defined as _____________________________________________
5. the most common force is that of gravity __________________________
6. attracts everything downwards to its surface ________________________
7. a measure of inertia ___________________________________________
8. an unchanging intrinsic property _________________________________
9. revolves around the concept of density ____________________________
10. Archimedes’ principle states ____________________________________
11. an object immersed in a fluid ____________________________________
12. is equal to ___________________________________________________
13. the value of the principle lies ____________________________________
14. to measure both its mass and volume ______________________________
15. amount of water ______________________________________________

 

VIII. Fill in the missing words.

 

1. Statics is the branch of physics that ______ with the ________ of bodies.
2. The study of statics _________ crucially on an understanding of the concept of force.
3. Other forces include _______, which in some cases can act against another force to prevent movement.
4. Mass is _________ as the _________ of an object to any change of its state of motion or rest.
5. Mass is, therefore, a __________ of the ________ of an object.
6. The weight of an object depends on the _________ of the gravitational field acting on it.
7. _______ _______ is given by the density of an object divided by the density of water.

 

IX. Fill in the prepositions if necessary.

 

1. Statics is the branch ____ physics that deals ____ the behaviour ____ bodies that are held stationary ____ the influence of a system ____ forces.
2. Other forces include friction which ____ some cases can act ____ another force to prevent movement.
3. The action ____ a force depends ____ the mass ____ an object.
4. Mass is a measure ____ the inertia ____ an object.
5. It is the downward force of an object resulting ____ the action ____ the force ____ gravity.
6. Much ____ this work revolves ____ the concept ____ density.
7. Density is the mass ____ an object ____ unit volume.
8. The property is given ____ the density ____ an object divided ____ the density ____ water.
9. Archimedes found its density ____ putting the crown ____ a bowl ____ water.
10. The weight ____ an object is equal ____ the weight ____ fluid displaced.

 

X. Define whether the sentences are true or false.

 

1. Statics is the branch of physics.
2. The study of statics depends crucially on an understanding of the concept of quantum.
3. The most common force is that of gravity which on earth attracts everything downwards to its surface.
4. Mass is defined as the attraction of objects to each other.
5. Mass is, therefore, a measure of the energy of an object.
6. The weight of an object is an unchanging intrinsic property.
7. One of the major areas of study in statics is the behaviour of objects in fluids.  

 

XI. Practice with someone asking and answering.

 

1. What is statics?
2. What does the study of statics depend on?
3. Give the definition of the force.
4. What are the examples of different forces?
5. What does the action of a force depend on?
6. In what way is mass defined?
7. Is the weight of a body an unchanging intrinsic property?
8. It is the downward force of an object resulting from the action of the force of gravity, isn’t it?
9. What is one of the major areas of study in statics?
10. What concept does much of this work resolve around ?
11. What do you know about specific gravity or relative density?
12. What does Archimedes’ principle state?

 

XII. Put questions to the following statements.

 

1. Statics deals with the behaviour of bodies.
2. Mass is a measure of the inertia of an object.
3. Archimedes found the density of the gold crown.

 

XIII. Dictate the following statements in English to your fellow-students.

 

1. Statics is the branch of physics that deals with the behaviour of bodies.
2. The most common force is that of gravity which on earth attracts everything downwards to its surface.
3. Other forces include friction and viscous force.
4. Density is the mass of an object per unit volume.

 

XIV. Dictation-translation.

 

1. Статика – это область физики, которая исследует поведение тел, которые удерживаются в неподвижности под влиянием системы сил.
2. Изучение статики зависит в значительной степени от понятия «силы», которую можно определить как фактор, способный изменить состояние покоя или движения тела.
3. Другие силы включают силу трения, которая в некоторых случаях действует в противоположном направлении по отношению к другой силе и тормозит движение, и силу вязкости, которая действует в противоположном направлении по отношению к силе гравитации.
4. Действие силы зависит от массы тела, на которое она оказывает воздействие.
5. Массу тела можно определить, как сопротивление тела любому изменению состояния движения или покоя под воздействием силы.
6. Хотя масса тела является неизменной повсеместно, его вес зависит от напряженности гравитационного поля, воздействующего на него.
7. Одна из главных областей исследования в статике – это поведение тел в жидкостях и газах.
8. Значительная часть исследований вращается вокруг понятия «плотности», которую можно определить как массу тела на единицу объема.
9. Закон Архимеда гласит, что на всякое тело, погруженное в жидкость, действует со стороны этой жидкости выталкивающая сила равная весу вытесненной телом жидкости, направленная вверх и приложенная к центру тяжести вытесненного объема.
10. Ценность закона Архимеда состоит в том, что он дает возможность определить удельный вес и плотность тела, не прибегая к измерению массы и объема.