10. Make up dialogues on the following topics using the

Introductory and connective words.

1. The definition of machine. 2. The arragement of the simplest machines. 3. The mechanical laws underlying the operation of the simplest machines. 4. The simplest machines applications.

the reason is, in order to, depending on, because, concerning, that is why, hence, thus, so, therefore, since, if…then, taking into consideration that, proceeding from the fact that, first…then, after that, it can be viewed, the reason / thing is.

11. A) Consider the Linerar Equations and tell whatever you studied on the topic.

Equations in which the highest power of the variables is the first, are called equations of the first degree. Thus, y = 3x + 5, y = 2 ─ 7x and

y = 0.3x ─ 0.5 are all equations of the first degree. All equations of this type give graphs which are straight lines and hence they are often called linear equations.

12. Translate the text into English. Блок

Блок (англ. block, нім. Вlоск, франц. bІос) — 1) Механізм у формі колеса з жолобом по ободу, через яке перекинуто канат (трос, ланцюг).

2) Сукупність вуз­лів, пристроїв, споруд або яких небудь частин (деталей), об'єднаних за призначенням, розміщенням тощо (турбінний блок електростанції, блок харчування). 3) Вузол ма­шини з кількох однакових частин, наприклад, блок циліндрів у двигуні внутрішнього згоряння. Комбінація нерухомого та рухомого колес називається блок і трос (таль, поліспаст), робить блок більш зручною, простішою машиною. Нижнє чи рухоме колесo збільшує нашу силу вдвічи (незважаючи на тертя), а верхнє

або фіксоване колесо змінює напрямок сили.

Text 2

1. Read and retell the text.

The Lever

The lever is a bar with a support, called a fulcrum. A lever can increase

the applied force, as in a crowbar or the use of a hammer to pry up nails; or it can increase the speed or distance of a force, as in a baseball bat or fishing

pole. But it cannot increase the force and the speed at the same time; it may do only one of these things. Compound ma­chines are merely arrangements of two or more simple machines.

Fig. 11. In order to raise the load of 120 pounds located at 1 foot from the fulcrum, an effort of 12 pounds is needed at 10 feet from the fulcrum.

Mechanical Advantage. A beam balance, which is a kind of lever. At a distance 6 units to the left of the fulcrum, a double weight is hanging. Suppose we wish to balance this weight by hanging a single weight on the right. At what distance from the fulcrum must we hang the weight? Experiment would quickly show that this distance is 12 units. By performing more experiments of this sort we would find that, in all cases, the weight on the left times its dis­tance from the fulcrum equals the weight on the right times its distance from the fulcrum. (In this case, 2 X 6 = 1 X 12).

The number of times a machine increases the applied force is called the

mechanical advantage (MA) of the ma­chine. It can be found by dividing the

resistance (R), which is the weight of the object moved, by the effort (E), which is the force applied. So if a 120-pound rock is moved by a 12-pound force, the MA is 10:

= = 10

There is another, equally simple, way to compute the MA. The distance from the fulcrum to where the effort is exerted is called the effort arm (EA), and the distance from the fulcrum to where the resistance is exerted is called the re­sistance arm (RA). The MA is computed by di­viding the EA by the RA. For example, in Figure 1 the EA is 12 feet and the RA is 6 feet; the MA is therefore 12/6, or 2. In Figure 2 the EA is 10 feet, the RA is 1 foot, and the MA is 10.

Distance vs. Effort. It should be pointed out, however, that we are not getting something for nothing. In Figure 2, although we exert only 12 pounds of force to raise a 120-pound load, our 12-pound force has to move through a greater distance than the load. For example, if we push the end of the lever down one foot, the load will be raised only about one inch.

In physics, work is defined as the product of a force and the distance

through which the force is exerted. A common unit of work in English units is the foot-pound, equal to the work done by a force of one pound exerted through a dis­tance of one foot; and the basic metric unit of work is the joule, equal to a force of one newton exerted through a distance of one meter. In the example above, if we push the end. of the lever down by one foot, we have put in 1 foot x 12 pounds, or 12 foot-pounds, of work. If the load is raised one inch, then the work done on the load is 1/12 foot x 12 pounds, or again 12 footpounds.