Ре­ше­ние

WELLS

ENGINES

The two most common types of engine for land vehicles are the petrol engine and the diesel engine.

Petrol engines are usually lighter and smaller than diesel engines. This makes them cheaper, and this is why most cars and motorbikes use petrol engines. Petrol engines are also less noisy than diesel engines. They usually go faster. On the other hand, diesel engines use less fuel and last longer than petrol engines, and this is why larger vehicles such as trucks and trains use them. They are also safer than petrol engines, because their is less danger of fire.

There are two main types of petrol engine—4-stroke and 2-stroke. All cars and larger motor-cycles use 4-stroke engines. But most smaller motorbikes use 2-stroke engines. These are lighter and smaller than 4-stroke engines, and are therefore cheaper.

Look at the three types of wells in FIG. 1. Well A is the simplest of the three. It consists of a pipe, a point and a pump. You hammer the pipe into the ground until the point is below water level. The pipe is usually less than 10 mm wide and less than 20 m long. The width of the hole is the same as that of the pipe. Well В is the cheapest because it has no pump. It uses a bucket and rope. The hole is usually more than 1 m wide. Well В is usually about the same depth as Well A.

The best (and most expensive) well is C. The hole is usually less than 0.3 m wide, and the pipe has the same width as the one in Well A. The depth is usually more than 20 m. Well С uses a pump.

What are the objects in Fig. 1 called?

How to weld (Electric Arc)

1 Hold the screen in front of your eyes.

2 Hold the electrode at 80° to the surface of the plates.

3 Make sure that the tip of the electrode is less than 3 mm

from the plate.

4 Strike an arc between the tip and the plate.

5 Move the electrode steadily backwards in a straight line (see FIG.).

What do the letters in FIG. 1 and FIG. 2 refer to?

How to mix concrete by hand

Concrete is made from cement, aggregate and a small amount of water. The aggregate is both coarse (e.g. stones and gravel) and fine (e.g. sand). The coarse aggregate, fine aggregate and cement are usually in the ratio 4:2:1.

1 Put two shovelfuls of sand into a wheel-| barrow

.

2 Add a shovelful of cement.

3 Mix these thoroughly with a shovel.

4 Add four shovelfuls of gravel. Mix thoroughly.

5 Make a hollow in the middle. Add a little

water with a hose. CAUTION: Do not

add all of the water—only a little.

6 Mix the materials thoroughly.

7 Add more water and mix again until the

concrete is the correct thickness.

A car cooling system

How to install a socket

1

The recess and the channel (see FIG. 1) are marked out with a pencil.

2 The plaster is cut away using a hammer and a chisel.

3 The brickwork is removed by drilling holes in it and then cutting it away with the hammer and chisel.

4 The box is inserted in the recess and screwed into place.

5 The cable is placed in the channel.

hannel holt-

Pig i

6 It is then pulled through the hole in the box.

7 The cable channel is covered. This is done by filling it with plaster, which is then painted or papered.

8 The socket is connected to the cable by inserting each wire in the terminal and tightening the screw (see FIG. 3).

9 The socket is screwed to the box.

1 What are the objects in the diagrams called?

Example: (a) This is called a chisel, (b) This is called plaster.

Making a car panel

This panel (FIG. 1) fits

onto- the front right-hand

side of a car. It is made

by three methods. \

First, sheet steel is made. This is done by pushing a piece of steel between two rollers (see FIG. 2), which squeeze the metal and make it longer and thinner. This method is called ROLLING. Not all metals can be rolled. For example, iron cannot be rolled because it is too brittle. But steel can be rolled because it is tough and malleable enough.

Next, the steel is cut into a flat shape (see FIG. 3). This is done by placing the i sheet onto a die, and then cutting a hole in it with a punch. The method is called \ PUNCHING. The steel can be cut easily because it is now very thin.

Finally, the sheet steel is bent and pressed into a rounded shape (like in FIG. 1). This is done by putting the sheet onto a die and then bending the sheet around the die with a press (see FIG. 4). This method is called PRESSING. It is not ] difficult to press sheet steel because it is thin and malleable.,

1 What are the objects in the diagrams called?

PAINTING EQUIPMENT

First, you need paint brushes. There are three main types: broad, narrow and angled. Use the broad brush for broad flat areas such as walls. Use the narrow one for corners. And use the angled one for window frames and difficult angles.

Next you need a roller for painting flat surfaces smoothly. Use a long extension on the handle for reaching high places, such as ceilings.You will also need a tray for holding the paint and the roller.

Next, you need a paint pot for holding the paint and the brush. Make sure that the mouth of the pot is wide enough for the widest brush, and that it is small enough to carry.

Next, you need a stepladder for climbing up to the job, a scraper for scraping off old paint and paper from the walls, cloths for covering the furniture, and rags for cleaning paint off the floor.

Finally, you need turpentine for cleaning the paint brushes and rollers.

1 What are the objects in the picture called? (Note: look at the letters (a), (b), (c), etc.)

CAUTION: Welding can be dangerous. Any of these accidents might happen to you: (a) you could be blinded by sparks; (b) you could get an electric shock; (c) your face, body, arms, legs or feet could be burnt; (d) there could be a fire in the workshop.

PROTECTIVE CLOTHING

1

A mask or helmet must be worn in electric arc welding. (In gas welding, goggles can be used.)

2 Clothes must be kept dry and clean.

3 Thick, heavy boots must be worn.

These must be made of some insulating material such as rubber.

4 Gloves, and apron and a cap must be worn.

5 Overalls must have long sleeves and no pockets or cuffs.

WORKSHOP

6 The floor must be made of concrete.

7 There must be a metal container on the floor for the sparks.

8 What are the objects in Fig. 1 called?

Use*of ladders - Safely Rules

CAUTION: A ladder can be a very dangerous tool. Any of these accidents could happen to YOU. (a) The ladder could slip on an oily floor and you could fall off; lb) the top could fall backwards; (c) a door could open and push the ladder backwards or to the side; (d) a metal ladder could touch an electric wire and give you an electric shock; (e) a ladder could fall off boxes or drums.

FOLLOW THESE RULES.

1 Metal ladders, or wooden ones with metal wires must never be used for electrical work.

2 Wet or oily floors must be cleaned before a ladder is lifted.

3 When the ladder is near a door,

3.1 the door must be locked or closed,

3.2 the door must be blocked open, or

3.3 there must be a man at the bottom.

4 The foot of the ladder must be fixed.

5 The ladder must NEVER be placed on drums, boxes, etc.

6 The top must be fixed. It should be tied to poles, etc, using hooks, chains, ropes or a strap.

Findinga fault in a car

If your car doesn't start in the morning, you should check three things first: the battery, the fuel level and the spark plugs. It is easy to repair these faults. If the battery is flat, you should recharge it. If this doesn't work, you should replace it If the petrol tank is empty, fill it up. If the spark plugs are dirty, clean them, and if the gap in a spark plug is too narrow or too wide, adjust it to the correct width.

If your car still doesn't start, the petrol pump may be broken, or the fuel pipe may be blocked. If the pump is broken, it must be repaired or replaced. If the fuel pipe is blocked, take it off and unblock it.

If there is a loud CLICK! when you turn the key, the starter motor may be jammed. If it is, you can try to release it by pushing the car forwards and backwards (in 2nd gear). If the car still doesn't start, the starter motor should be repaired or replaced.

Buildinga road

First, the earth is removed using bulldozers and diggers.

Then the ground is levelled. This is done by cutting the top layer until it is flat and level.

Next a layer of gravel (approximately 300 mm thick) is spread over the ground.

Finally the top layer is added. There are two main types: blacktop and concrete. If it is a blacktop road, layers of hot tarmacadam are poured onto the gravel and pressed down using rollers. The total layer of blacktop materials is approximately 300 mm thick. If it is a concrete road, the concrete is laid on top of the gravel. The concrete slabs are usually approximately 250 mm thick and 4.5 m long.

Accidents in the machine shop

1 A piece of metal from the grinding machine went into Mr A's right eye and cut it. Cause: He did not use the guard on the machine.

2 Mr В cut his hand on the drilling machine. Cause: He removed a piece of metal from the machine with his hand.

3 Mr С cut his finger with a saw. Cause: He held the workpiece on the bench with his hand.

4 Mr D slipped on the floor, fell against a machine and cut his head. Cause: There was some oil on the floor. Mr D walked too quickly and did not see the oil.

5 Mr E climbed a metal ladder and got an electric shock. Cause: He placed the ladder against some electric wires.

6 There was a fire in the storeroom. Cause: an old switch that wasn't screwed tightly to the wall caught fire when Mr F used it.

7 Mr G got an electric shock. Cause: He poured water onto the fire.

Who broke the following safety rules?

Example: (a) Mr С broke this rule.

(a) ALWAYS HOLD WORK IN A VICE

(b) ALWAYS WEAR GOGGLES AND USE THE/GUARD WHEN OPERATING GRINDER

(c) ALWAYS CLEAN MACHINES WITH A BRUSH - NEVER WITH YOUR HAND

(d) NEVER USE SWITCHES THAT ARE DAMAGED

(e) LADDERS MADE OF METAL MUST NEVER BE USED NEAR ELECTRICAL WIRES

(f) FIRES WHICH ARE CAUSED BY ELECTRICAL FAULTS MUST NEVER BE EXTINGUISHED WITH WATER

(e) ALWAYS KEEP WORKSHOP FLOORS CLEAN AND FREE FROM OIL

Accident Report

At about 10.40 yesterday morning. Bill and I carried the long 8 m ladder to the building site. We placed it near the scaffolding. We lifted it in the correct way:

— First, we placed the ladder on the ground at 90° to the wad. The foot was 2 m from the wall.

— Bill held down the foot of the ladder.

— I lifted the top above my head.

— I then walked slowly forward.

lifting the ladder slowly upwards. Suddenly, when the ladder was vertical in the air, a strong wind blew. The ladder moved to the right towards the scaffolding. It hit the scaffolding and then fell downwards and towards Jim (who was on a platform at the bottom of the scaffolding.) The ladder hit him and he fell against the scaffolding and cut his head.

I I I I I I I I

Сумма смеж­ных углов равна 180°, от­ку­да Тре­уголь­ник ABC — рав­но­бед­рен­ный, по­это­му Сумма углов тре­уголь­ни­ка равна 180^\circ, сле­до­ва­тель­но,

Ответ: 112.

Ответ: 112

14 Точка D на сто­ро­не AB тре­уголь­ни­ка ABC вы­бра­на так, что AD = AC. Из­вест­но, что ∠ CAB = 19° и ∠ ACB = 160°. Най­ди­те угол DCB. Ответ дайте в гра­ду­сах.

15 В тре­уголь­ни­ке ABC AB = BC =85, AC = 102. Най­ди­те длину ме­ди­а­ны BM.

16 Вы­со­та рав­но­сто­рон­не­го тре­уголь­ни­ка равна Най­ди­те его пе­ри­метр.

17 Сто­ро­на ромба равна 32, а ост­рый угол равен 60°. Вы­со­та ромба, опу­щен­ная из вер­ши­ны ту­по­го угла, делит сто­ро­ну на два от­рез­ка. Ка­ко­вы длины этих от­рез­ков?

18 Най­ди­те угол АDС рав­но­бед­рен­ной тра­пе­ции ABCD, если диа­го­наль АС об­ра­зу­ет с ос­но­ва­ни­ем ВС и бо­ко­вой сто­ро­ной АВ углы, рав­ные 30° и 50° со­от­вет­ствен­но.

19 Сумма двух углов рав­но­бед­рен­ной тра­пе­ции равна 220°. Най­ди­те мень­ший угол тра­пе­ции. Ответ дайте в гра­ду­сах.

20 Най­ди­те мень­ший угол рав­но­бед­рен­ной тра­пе­ции, если два ее угла от­но­сят­ся как 37:53. Ответ дайте в гра­ду­сах.

21 Тан­генс остро­го угла пря­мо­уголь­ной тра­пе­ции равен 2. Най­ди­те её боль­шее ос­но­ва­ние, если мень­шее ос­но­ва­ние равно вы­со­те и равно 78

22

Ос­но­ва­ния тра­пе­ции равны 1 и 11. Най­ди­те боль­ший из от­рез­ков, на ко­то­рые делии сред­нюю линию этой тра­пе­ции одна из её диа­го­на­лей.

23

Ос­но­ва­ния рав­но­бед­рен­ной тра­пе­ции равны 33 и 75, бо­ко­вая сто­ро­на 75. Най­ди­те длину диа­го­на­ли тра­пе­ции.

24 Около тра­пе­ции, один из углов ко­то­рой равен 44°, опи­са­на окруж­ность. Най­ди­те осталь­ные углы тра­пе­ции

25 В тра­пе­цию, сумма длин бо­ко­вых сто­рон ко­то­рой равна 30, впи­са­на окруж­ность. Най­ди­те длину сред­ней линии тра­пе­ции.

26 У тре­уголь­ни­ка со сто­ро­на­ми 15 и 3 про­ве­де­ны вы­со­ты к этим сто­ро­нам. Вы­со­та, про­ведённая к пер­вой сто­ро­не, равна 1. Чему равна вы­со­та, про­ведённая ко вто­рой сто­ро­не?

27 В тре­уголь­ни­ке ABC про­ве­де­на бис­сек­три­са AL, угол ALC равен 148°, угол ABC равен 132°. Най­ди­те угол ACB. Ответ дайте в гра­ду­сах

28 В тре­уголь­ни­ке ABC BM — ме­ди­а­на и BH — вы­со­та. Из­вест­но, что AC = 88 и BC = BM. Най­ди­те AH.

29 В ост­ро­уголь­ном тре­уголь­ни­ке ABC вы­со­та AH равна а сто­ро­на AB равна 95. Най­ди­те cos B.

30 В тре­уголь­ни­ке ABC AB = BC, а вы­со­та AH делит сто­ро­ну BC на от­рез­ки BH = 48 и CH = 2. Най­ди­те cos B.

31 Углы, от­ме­чен­ные на ри­сун­ке одной дугой, равны. Най­ди­те угол . Ответ дайте в гра­ду­сах.

32 Пря­мые m и n па­рал­лель­ны. Най­ди­те ∠3, если ∠1 = 22°, ∠2 = 72°. Ответ дайте в гра­ду­сах.

33 Най­ди­те ве­ли­чи­ну угла AOK, если OK — бис­сек­три­са угла AOD, ∠ DOB = 64°. Ответ дайте в гра­ду­сах

34 В тре­уголь­ни­ке ABC угол C пря­мой, BC = 9, sin A = 0,3. Най­ди­те AB

35 Два ост­рых угла пря­мо­уголь­но­го тре­уголь­ни­ка от­но­сят­ся как 2:43. Най­ди­те боль­ший ост­рый угол. Ответ дайте в гра­ду­сах

36 В тре­уголь­ни­ке угол равен 90°, . Най­ди­те .

Дата добавления: 2015-07-13