After we have studied this unit, we will be able to
Key words : circular rotate axis propeller turbine mobility journey (v) vehicle invention civilisation
Human beings have invented many important things so far. They have brought great civilization to the world through these inventions. Do you know which invention is the greatest? It is 'the wheel'.
A wheel is a circular object. It can rotate around its axis and help easy movement of things across a surface.
The wheels are, in fact, everywhere. They are on our cars, trains, planes, wagons and so on. Besides, they are on most factory and farm equipment. Fans, propellers, turbines are also other types of wheels.
So the wheel is very important. We cannot imagine modern life without wheels. But do we know exactly who made the first wheel?
Questions
difficult much circular important heavy first |
Although the wheel is a very (a) ------ invention, the history of its origin is unknown. Experts guess that the first wheel was developed from a circular object. The early man observed that a huge piece of stone could be rolled easily if it was (b) ------ in shape. Similarly, a heavy tree-trunk is (c) ------ to carry; but it can be rolled away with less effort. Even, a gigantic tree-trunk can be moved easily using other small and round trunks as rollers under it. Thus, early man took advantage of rolling objects and developed the (d) ------ wheel. Apart from its mechanical advantage, a wheel's mobility has contributed (e) ------ to the civilisation.
1. The wheel 2. A plain wheel 3. It 4. A propeller |
is has rotates | a type of wheel. around its axis. one of the simplest machines. wheels on vehicles and machines. helped in rapid progress of civilisation. |
Key words : invent valley ancient further pioneer warfare
Mr Ramis : You know that the invention of the wheel has helped to create a new civilisation. But do you know who first used wheels?
Rubina : No teacher. But I guess it may be the Greeks.
Mr Ramis : The Greeks were pioneers in many things. But in this case, however, the Mesopotamians were the first. The oldest ever wheel was discovered in Mesopotamia. It was in 3,500 B.C.
Rubina : Where is Mesopotemia?
Mr Ramis : Well, Mesopotamia was in ancient Iraq. It was along the valley of the rivers Tigris and Euphrates. After the Mesopotamians, the wheel was further improved by the Egyptians. They first made wheels with spokes. Then they used them on chariots around 2000 BC.
Rubina : So the wheel travelled to Egypt from Mesopotamia?
Mr Ramis : Exactly. But it travelled eastwards too. Wheels reached the Indus valley by 3000 B.C. But chariots with spoked wheels were made in ancient India in around 1500 B.C. They were used for war, hunting and racing.
Rubina : What about the Greeks, teacher? Didn't they use wheels?
Mr Ramis : They definitely did. In 1500 BC, the Greeks too learnt the idea of wheel-making from the Egyptians. They also made further improvements on it. Later, the Romans did the same too and produced a variety of wheeled vehicles.
U9, L2 E Listening text: 10 |
F. Discuss in pairs and make as many 'Wh' questions as you can from the given answers below. First one is done for you.
1. i) Where does Mesopotamia lie?
ii) Which countries does Mesopotamia lie between?
Ans : Mesopotamia lies between India and Egypt.
2. -----------------------------------------?
Ans : The Caspian Sea is on the north of Mesopotamia.
3. -----------------------------------------?
Ans : The Nile falls into the Mediterranean Sea.
4. ----------------------------------------?
Ans : The river Yangzi lies to the east of India.
5. ----------------------------------------?
Ans : The Tigris and Euphrates run on the west of Mesopotamia.
Key words : high-speed record-breaking network expand conventional unconventional magnetic trainset
The TGV (Train à Grande Vitesse, meaning high-speed train) is France's high -speed rail service.
It started in the 1970s. Originally, it was powered by gas turbines. But in 1973, the TGV was changed into electric trains. The TGV service first started between Paris and Lyon in 1981. Later, the network connected other cities in France with Paris.
A TGV test train set the world record for the fastest conventional wheeled train on 3 April 2007. It reached the speed of 574.8 km/h (357.2 m/h) on the test run. But the regular TGV trains operate at the highest speed of 320 km/h (200 m/h). It is the present world record of speed of a conventional commercial train.
The Bullet Train is the network of high-speed train service in Japan. It started operation in 1964 on a limited route. But at present, most major cities of Japan come under the network.
The Bullet Train runs at a maximum speed of 300 km/h (186 m/h). It plans to increase speed up to 320 km/h (200 mph). In 2003, Japan set the world record for unconventional magnetic trainsets. In a test run, the speed was 581 km/h (361 mph). But it is not yet in regular commercial operation.
The High-speed Rail
The High-speed Rail service in China started operation on April 18, 2007. Currently China has started building a high-speed passenger rail network. It will be similar to French TGV or Japanese Bullet Trains. The usual top speed of China's conventional quick trains is 300 km/h (186 mph).
Recently China has set the world record of a speed of 487.3 km/h (303 mph). In 2011, this record was set by an unconventional magnetic trainset called the "Harmony Express". This is the highest speed of an unconventional magnetic trainset in regular commercial operation.
Name of the country | Name of the train/train network | Year of introduction/ start | Top of speed conventional train | Top speed of unconventional train | Holds world record for |
Name: Bangladesh Railway
For example:
1 What is the official name of our rail service?
2 Where is the headquarters of Bangladesh Railway?
Now continue...
Key words : endeavor supersonic speed revolution aviation ads website neither ground (v) sky's the limit
Human beings conquered the distance on earth by discovering wheels. They endeavored further. Then on December 17, 1903, the Wright brothers in America made the first experiment of flying in a plane. In the experiment, a machine carried a man and rose above by its own power. The machine was called 'aka airplane'. It flew naturally in a smooth speed, and finally landed without damage. That was human being's first real take-off. And now, they have got a supersonic speed. In a supersonic speed, something travels faster than sound! So the sky's the limit now!
Modern aircraft companies are making revolutions in aviation technology. Boeing as well as Airbus is producing modern passenger airplanes. These planes fly very fast, Boeing 787 flies 950 km/h. However, Airbus 350 is expected to fly at a speed of 945 km/h.
You find attractive ads on the websites of both Boeing and Airbus planes. Both have excellent features. But in speed, neither could beat the Concorde. It is the
world's fastest supersonic passenger aircraft. Its normal speed was 2,170 km/h. The Concorde was a joint project by France and Britain. It started passenger flight in 1976. Unfortunately, the Concorde fleet was grounded forever in 2003 after a major accident.
Questions
Note : The speed of sound, which is approximately 760 miles per hour is called 1 Mach. An airplane flying less than 1 Mach or less than 760 miles per hour is travelling at subsonic speed. Faster than 1 Mach or 760 miles per hour would be a supersonic speed.
Sohan : Teacher, in the last class we read about modern aircraft. There were Boeing 787s, Airbus 350s, Concorde and so on. But which one is the best? Which one can we buy for our Biman Bangladesh Airlines?
Mr Ramis : A difficult question. There are certain things to consider. If you think of speed, Concorde flies the fastest. To many, it looks the most beautiful. But it's no more in operation.
Sohan : Between the other two aircraft?
Mr Ramis : Well, if you remember, Boeing 787 travels 950 km/h. So you see, it's not as fast as Concorde. But it's faster than Airbus 350.
Sohan : Yes, teacher. I remember Airbus 350 travels 945 km/h. It's 5 km shorter than Boeing 787.
Mr Ramis : Nice calculation! But there are other factors too. Say, passenger capacity, production cost and many more. Airbus 380 now is the largest and can carry more passengers than any other aircraft. Authorities have to consider so many...
Sohan : Yes, teacher. I understand.
Complete these statements using the correct form of words in the brackets.
Key words : withstand space base launch detach monitor hypersonic research melting point
The Falcon Hypersonic Technology Vehicle-2 (Falcon HTV-2) is the fastest plane ever built by human beings. It would fly from London to Sydney in less than an hour. Supersonic Concorde, by the way, could not fly at such a great speed. At the same time it would withstand temperatures of almost 2,000 degree C. This temperature is hotter than the melting point of steel.
The US Defense Agency will launch the Falcon HTV-2. First, they will set it on the back of a rocket. Then they will launch both into the space from an Air Force Base. The plan goes like this: engineers will launch the Falcon HTV-2 into the space on the back of a rocket; then they will detach the plane from the rocket; the plane Falcon will fly towards the Earth; engineers will guide and monitor it in its flight. The plane would fly at hypersonic speed of 13,000 mp/h. This speed is about 20 times the speed of sound.
The Falcon was born in 2003. It was born as part of a US military project. The project researched and built a special type of plane. The researchers wanted that the plane could reach any part of the world in less than an hour. They also wanted to use it for any purposes, military or civil. The plane was already tested in computer models.
The Falcon Hypersonic Technology Vehicle-2 would be mankind's dream aircraft in the days to come.
Questions
U9, L5 D Listening text: 11 |
E. The following passage is based on the information in section B. Read the text in B again. Discuss in pairs and complete the following sentences with will/would, can/could/could not.
Even Concorde --------- fly as fast as Falcon HTV-2. The news report fly as fast as Falcon HTV-2. The news report -------- launch the Falcon Hypersonic Technology Vehicle-2 into space. Scientists expect that the Falcon HTV-2 -------- fly at 13,000 miles per hour. The US military wishes that the Falcon ------- bomb any part of the world in less than an hour in the future. Engineers plan that they --------- set the Falcon on the back of a rocket to launch it into the distant space.
If you fly westward in a supersonic plane such as Concorde, you will land several hours before you took off. Can you explain how?
Key words : record paper surface of stone bark encyclopedia wood plunk digital
Communication of ideas is at the centre of civilisation. It needs written records. Most of our records in the modern age are on paper. Though writing was invented very early, paper is a more modern invention.
For long in history, people exchanged ideas through speaking and listening. Then there came the art of writing. But to record thoughts in writing was difficult. Writing materials were not available. People used the surface of stone, metal, wood, bark, leaves, etc. for writing. Those things were not easy to carry. Then for ages, people looked for easy writing materials. Finally, paper was invented in China in 105 AD.
Before the paper age, knowledge was very restricted. Can you think of that time? There were very few books in the world. Maybe, they were written on stone or on heavy wood plunks or on metal sheets. Suppose, one page was a heavy stone block. So, think of a hundred-page book! In our age, you can carry the entire world of knowledge in digital form in your laptop bag. You can even carry a huge volume of paper encyclopedia. But who could produce and carry tons of heavy stone books and documents in those paperless days? In fact, paper has made publication and the spread of knowledge and information easy. So, you can see how paper has changed our life.
Questions:
U9, L6 D Listening text: 12 |
1. He took the bark of mulberry tree and bamboo fibre. |
2. He mixed them ……………………….. |
3. He pounded ………………………. |
4. He poured the mixture ………………………… |
5. He let the water ......……………… |
6. He let the thing dry. |
Contemplation
For days and days I've climbed a tree
A dappled yellow tree
And gazed abroad at many things
I've always wished to see.
I see the green and gentle fields
All bounded in with hedge
And shining rivers swimming through
The rushes on the edge,
And little sheep who play all day
I watch them as they run,
While far away the roofs of town
Are shining in the sun.
I think it's very nice to sit
So high and look so far----
How very large the world can be!
How many things there are!
John Carpenter
Note
dappled yellow tree - spotted yellow tree (the leaves may be yellow) gazed abroad - looked around
bounded - surrounded
hedge - a thick row of bushes swimming through - (the river like a person is swimming through) flowing through rushes - tall plants that grow on the river's edge
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