অষ্টম শ্রেণি — মাধ্যমিক Things that have changed our life MCQ Question Solution PDF
অষ্টম শ্রেণি — মাধ্যমিক Things that have changed our life MCQ (বহুনির্বাচনী) অংশের প্রশ্নসহ উত্তর মালা - ব্যাখ্যাসহ সমাধান, দ্রুত প্র্যাকটিস, মক টেস্ট, PDF ডাউনলোড করুন 72 টি প্রশ্ন
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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.
