Class 8 Things that have changed our life CQ Question Answer Solution PDF

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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?

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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 speeds 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 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.

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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.

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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.

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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, 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 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 CE.

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 time, you can carry the entire world of knowledge in digital form in your laptop. 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.

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,