Ex.3. Complete the following sentences with the information from the text.

1. Theoretical or general mechanics treats of…

2. The design and calculation of specific structures are based on…

3. Mechanical motion is…

4. The physical measure of  mechanical interaction is…

5. The general course of theoretical mechanics treats of …

 

Ex. 4. Match the adjectives and nouns they can be used with. Compose 6 own sentences with these expressions.

 

	Adjective		Noun
1	certain	a	motion
2	general	b	machines
3	mechanical	c	position
4	mutual	d	principle
5	natural	e	mass
6	reciprocal	f	science
7	relative	g	body
8	rigid	h	action
9	variable	i	interactions
10	various	j	variety
11	wide	k	laws

 

 

Ex. 5. Translate the following expressions into English.

Подразумевать механическое движение; относительное положение материальных тел в пространстве; стремиться изменить состояние движения; рассматривать что-либо; не принимать во внимание размеры материального тела; пренебрегать деформацией тела; естественная наука; общие законы движения и взаимодействия материальных тел; широкое разнообразие проблем; несмотря на разнообразие задач; законы, управляющие движением и равновесием материальных тел.

 

Ex. 6. Use the correct prepositions in the following phrases:

1. confront the engineer ….. problems

2. the solution, at least …part

3. laws derived … experience

4. the earth’s motion … the sun

5. phenomena associated…the motion

6. objects….study

7. mass changes …..time

8. mechanics treats …the general laws

9. be based … laws

10. according … the nature of objects

 

Unit 2.

 

Kinematics. Kinematics of a Particle.

 

Text 1. Kinematics

Learn the following words and word combinations by heart:

 

аcceleration	ускорение
be at rest change with time consequently consider define	находиться в состоянии покоя изменяться с течением времени следовательно считать, рассматривать определять, давать точное определение, характеризовать
determine	определять, устанавливать, измерять, вычислять
frame of reference locate	система отчета располагать, размещать, определять местоположения
path	путь, траектория
remain constant specify a position	оставаться постоянным, неизменным определить положение
take into account	принимать во внимание
velocity	скорость
algebraic ~ angular ~	алгебраическая скорость угловая скорость
average ~	средняя скорость
instantaneous ~ linear ~ zero ~	мгновенная  скорость линейная скорость нулевая скорость
with respect to = w r t	по отношению к…

Kinematics is the section of mechanics, which treats of the geometry of the motion of bodies without taking into account their inertia (mass) or the forces acting on them.

By motion in mechanics is meant the relative displacement with time of a body in space with respect to other bodies.

In order to locate a moving body (or particle) we assume a coordinate system, which we call the frame of reference or reference system, to be fixed relative to the body with respect to which the motion is being considered. If the coordinates of all the points of a body remain constant within a given frame of reference, the body is said to be at rest relative to that reference system. If, on the other hand, the coordinates of any points of the body change with time, the body is said to be in motion relative to the given frame of reference (and consequently, relative to a body which is fixed with respect to the frame of reference).

To describe the motion, or the law of motion, of a given body (particle) kinematically means to specify the position of that body (particle) relative to a given frame of reference for any moment of time. The principal problem of kinematics is that of determining all the kinematics characteristics of the motion of a body as whole or of any of its particles (path, velocity, acceleration etc.) when the law of motion for the given body is known.  

Comprehension  check.

 Ex.1. Answer the following questions:

1. What does motion mean in mechanics?

2. When is the body said to be at rest?

3. What happens  when the coordinates of any points of a body change with time?

4. What is the principal problem of kinematics?