Ex.2. Answer the following questions .

1. What does a rigid body imply? What are its main characteristics?

2. What are  the problems of kinematics of rigid bodies?

3. What is translation?

4. What is the difference between  translation and rectilinear motion?

5. What theorem defines the properties of translational motion?

6. Why is the length and direction of  constant?

7. What definitions can we give to the velocity and the acceleration of translation?

 

Ex.3. Say whether the following statements are True or False.

1.  The distance between any two points of a rigid body constantly changes during the whole period of motion.

2. Analysis of the motion of every point of the body in particular is one of the problems of kinematics of rigid bodies.

3. In translational motion, all the particles of a body move along similar paths.

4. Translation is another word for denoting rectilinear motion.

5. The accelerations of points A and B of a rigid body change in magnitude and direction all the time.

6. Translational motion of a rigid body is fully described by the motion of any point belonging to it.

7. In translational motion, if we superimpose the paths along which all the particles of a body move, the paths will be different. 

 

 

Ex.4. Match the terms and their definitions.

1	body	a	a quality or feature of sth that is typical of it and easy to recognize
2	curved	b	formed or moving in a straight line or consisting of straight lines
3	characteristic	c	a quality or power that belongs naturally to sth
4	determine	d	the science dealing with the forces that produce balance in objects that are not moving
5	path	e	an object that is separated  from other objects
6	property	f	a firm object or substance that has a fixed shape, unlike a gas or liquid
7	rectilinear	g	having a shape that is rounded and not straight
8	solid	h	the direction or line along which sb or sth moves
9	statics	i	to find out the exact details or fact about sth

  

Ex.5. Fill in the words from the text.

1. In kinematics we shall regard all solids as ….. bodies.

2.  In translational motion, all the particles of a body move …. ……. paths.

3. Let’s take two ……points A and B on the body.

4. The length of  is ……., because it is the distance between …….  …… of a rigid body.

5. The paths of particles A and B are …. …….. They will …… if superimposed.

Ex.6. Complete the following table:

 

Noun	Verb	Adjective
assumption
	define
		analytical
	move
consideration
		translational
straightness
		curved /curvy
	coincide

 

Ex.7. Translate into English.

1. Траектория, скорость и ускорение всех точек твердого тела одинаковы в любой момент времени.

2. Скорость поступательного движения - это общая скорость всех точек тела при поступательном движении.

3. Расстояние между любыми 2 точками твердого тела не изменяется в процессе перемещения.

4. Поступательное  и прямолинейное движение являются различными типами движения.

5. Тело перемещается относительно системы координат.

 

Unit 7.