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Exercises. Vocabulary. 6. Complete the text with the words from the box. Forces. Speaking. Discuss in pairs. How does each of these move?
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Exercises
Vocabulary
1. Transcribe the words:
thrust, artificially, aeronautical, strength, inequality, aerodynamical, perpendicular, axis, propulsion
2. Match the words from the texts (1-10) with the definitions (A-J):
| gravity | A | the things carried by a vehicle with scientific instruments and crew | |
| drag | B | the pressure of air that keeps something such as an aircraft up in the air | |
| lift | C | the reaction force that pushes an aircraft forward | |
| thrust | D | flight path | |
| force | E | the force of air that pushes against an aircraft or a vehicle that is moving forward | |
| weight | F | the height of an object or place above the sea | |
| altitude | G | how heavy something is when you measure it | |
| heading | H | the rate at which an object changes position | |
| velocity | I | a force that pulls objects | |
| payload | J | a push or pull t that causes, accelerates, or stops the motion of objects |
3. Explain in English and then translate the following words and expressions into Russian:
straight and-level unaccelerated flight, the pace of aeronautical development, to counterbalance these natural forces, the drag is supporting part of the weight
4. Match the words from the texts (1-5) with their synonyms (A-E):
| inherent | A | keep | |
| retardation | B | essential | |
| maintain | C | impressive | |
| dramatic | D | deceleration | |
| rearward | E | backward |
5. Find in the texts the English equivalents for the following expressions:
(1) для преодоления силы тяжести и сопротивления, (2) позволяет самолету летать, (3) аэродинамика самолета, (4) рассчитываются отдельно, (5) примерно в десять раз больше сопротивления, (6) в последующие десятилетия, (7) создание искусственных сил, (8) уравновесить природные силы, (9) комбинация двигателя и винта, (10) координированный полет с постоянной высотой и направлением, (11) любое неравенство между подъемной силой и силой тяжести, (12) самолет набирает высоту или снижается, (13) размер и тип двигательной системы, (14) выбранный во время полета, (15) относительная скорость ветра.
6. Complete the text with the words from the box
Forces
| push amount | forces motion | accelerate Scientists | opposite speed |
| direction | zipper | engines | pull |
How do you make something (1)? How do you make it move, change its (2) or (3) or stop? You give it a (4) or a (5). Pushes and pulls are examples of what scientists call (6). When you pull (7) at the on your jacket, you are using force. (8) designing a Moon rocket have to take into account all the forces that will act on it. These include not only the forces generated by its (9) to make it go, but also other forces that affect its (10), such as gravity. Force is described by the (11) of push or pull. It is also described by the direction of the push or pull. When you push on a door, you are using force in one direction. When you pull on that same door, you are using force in the (12) direction.
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7. Answer the following questions. Begin your answers with such introductory phrases as: as far as I know; as far as I remember; to my mind; certainly; it's hard to tell; probably; of course; if I am not mistaken, etc.
1) What forces act upon an airplane in straight- and-level unaccelerated flight?
2) How do birds create both lift and thrust to overcome the natural forces of weight and drag?
3) What forces do wings and engines produce?
4) What will any inequality between lift and weight result in?
5) What will any inequality between thrust and drag result in?
6) What is weight of an airplane determined by?
7) What is weight equal to?
8. Translate the following sentences into English:
1. Подъемная сила, сила сопротивления, сила тяги и вес действуют на самолет в полете.
2. Самолет находится в состоянии равновесия, когда сила тяга и сопротивление равны и противоположны по направлению.
3. Самолет будет продолжать двигаться вперед с той же равномерной скоростью.
4. Если сила тяги или сопротивления становится больше, чем противоположная сила, самолет теряет свое состояние равновесия.
5. Если тяга больше сопротивления, самолет будет ускоряться.
6. Если сопротивление больше тяги, самолет теряет скорость и в конечном итоге снижается.
7. Если подъемная сила больше веса, самолет будет подниматься.
Speaking
Conversation Questions: “Force”
Discuss in pairs. How does each of these move?
| bird | fly | grasshopper |
| helicopter | aircraft | bee |
Use the next words: horizontal, vertical, forwards, backwards, lift, fall, rotate, roll, hover, bank, dive, take-off, climb, withstand, accelerate, decelerate
| How to prepare for the Conversation ● Before speaking you should identify what can be accomplished by talking. Every communication act has a practical goal or goals (primary and secondary) ● Find information in newspapers, magazines, books, in-house literature, press releases or on the Internet ● Ask something and then go on to answer it yourself ● You must support your ideas with proof |
Writing
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Compose a written report about forces acting on the aircraft in flight.
Unit 8 Lighter-than-air aircraft
All aircraft are designed to fly through the air. But not all of them fly the same way. In fact, there are two types of aircraft. One is called “lighter-than-air. ” The other is known as “heavier-than-air. ” A lighter-than-air craft is able to float. It can become lighter in weight than the air around it. A circus balloon is a simple example of this type of craft. Before it gets filled, the balloon doesn’t move. Its weight keeps it down. But fill the bag with helium gas, and the balloon lifts up. Why does this happen? The reason is that helium is much lighter than air.
Why Kites Fly
A heavier-than-air craft is different. It always stays heavier than the air around it. This type of craft flies for another reason. Its surfaces cause moving air to lift up the craft. A simple heavier-than air craft is a kite. Kites come in many shapes and sizes. But they are all made to lift up in the wind. The kites people around the world fly for fun are named after the kite bird. This type of bird is also found all over the world.
Hot-Air Balloons
Most of us have seen them. Big and colorful, hot-air balloons carry people for long rides through the air. How do they do it? These lighter-than-air craft work in several ways. First, every hot-air balloon has an air-filled bag, or envelope. Because of its large size, the bag can move aside a lot of air. But air moved to another place pushes back. In fact, this displaced air presses so hard that it keeps the bag afloat. In other words, the bag is buoyant. But the basket tied to the bag stays on the ground. Its cargo of equipment and people is heavy.
To make the hot-air balloon go up, the pilot turns on a burner under the bag. The burner creates a flame. Hot air quickly rises into the huge bag. This heats up the air molecules inside. They start moving faster. Also, some of them escape through the bottom of the bag. That leaves fewer molecules inside. They are farther apart, too. The inside air, then, is less dense than the air outside, and it weighs less. The result? The hot-air balloon rises. To lower the hot-air balloon, the pilot turns off the burner. The air inside the bag gets cooler. That means the air molecules slow down. They also move closer together. Soon there’s room for outside air to re-enter the bag. More air molecules inside make the air in the bag denser—and heavier. So the craft comes down.
Floating Airships
Hot-air balloons can fly, but they cannot be steered. They simply float in whatever direction the wind takes them. An airship is a lighter than-air aircraft, too. But unlike a hot air balloon, the airship has an engine and fins. These allow the ship to be steered in the direction where the pilot wants it to go. The envelope of an airship is long and rounded. Usually helium gas issued to inflate it. The helium is sealed inside. Since helium is lighter than air, the envelope stays afloat.
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