Who built the first nuclear reactor? In 1942, Enrico Fermi was carrying out nuclear research at the University of Chicago in the United States. In the university squash court he and Leo Szilard built the world's first atomic pile, in which a chain reaction could be started and controlled. The pile was made of uranium blocks separated by graphite Cadmium rods could be inserted into the pile to halt the reactor.
A nuclear submarine is driven by turbine engines which use steam heated by a nuclear reactor. The submarine seldom has to return to part to refuel. The world's first nuclear powered submarine was the US Navy's Nautilus(1955). A lamp of uranium fuel the size of an electric light bulb provided enough energy to drive the submarine 100,000 kilometers. In 1960 the US nuclear submarine Triton sailed around the world under water in which a distance of 67,000 kilometers in three months without needing to refuel.
A single nuclear reactor can produce as much heat as 40 million, 100 watt lamps.
What's inside of nuclear reactor? Well inside of nuclear reactor is a uranium fuel which is sealed inside rods. The rods are arranged in groups called fuel elements.
A liquid(water or a molten metal) or a gas flows around the rods to cool them. Special control rods, made up of a substance which absorbs neutrons, can be raised or lowered, these rods stops the chain reaction. As an extra precaution against neutrons escaping, the elements are surrounded by a moderator. The moderator deflects neutrons back into the reaction to contain the dangerous radioactivity produced by the chain reaction, the reactor assembly is shielded by thick walls of steel or concrete.
A rack railway is a railway locomotive readily climbs steep hills since its wheels slip on the smooth rails. To climb mountains, a special system is needed. The first rack and pinions railway was built in 1811, but the system was not widely used until the 1870s. The train ‘claws’ its way uphill by means of a toothed pinion, or gear wheel, which engages with the rack which is a third rail with teeth cut into it.
This ensures that the train cannot slip. The Mount Washington Cog Railway in New Hampshire, USA, was built in 1869 and is still working. The steepest rack railway is the Mt. Pilatus Railway in Switzerland, built in 1889, with a highest gradient of 1 in 2.
A German baron, Karl Friedrich, Christian Ludwig, Drais von Sauerbronn, caused a stir in 1813. He appeared in the streets of Mannheim, seated astride a two-wheeled machine which he pushed along with his feet. People laughed at his so-called ‘running machine’ and were astonished that a man could keep his balance on two wheels, set one behind the other.
Drais established that he could travel four times as quickly as a walker, and his machine sparked off a new craze. Similar machines, called Dandy Horses, were soon beng ridden in stylish parks all over Europe.
The planets have been moving ever since the formation of the solar system. They were given their starting “push” then, millions of years ago, and have kept moving ever since around the sun. The sun’s enormous gravitational strength holds the planets in orbit around it.
They keep moving because there is no force in the solar system powerful enough to stop them and because there is no frictional force opposing them. There is no wind confrontation as in our ambiance.
Around the Earth is a layer of gas zone which is a figure of oxygen. This layer protects us from harmful ultraviolet rays given off by the Sun. Scientists have discovered that there is a hole in the ozone layer above Antarctica; it appears during the winter and closes up again in summer.
They believe the hole may indicate that air pollution, and especially the release of certain chemicals from aerosol sprays which can cause damage to the ozone layer.
Van Allen Belts - Far out on the outer edge of the atmosphere are two doughnut-shaped regions of radiation, known as the Van Allen Belts. The belt is made up electrically charged particles held in place by the Earth’s magnetic field.
The belts are the strongest over the equator and the weakest over the poles. The belts were discovered by the US Explorer 1 satellite in 1958 and named after James Van Allen, who designed and planned the research that found them. The belts shield the Earth from destructive cosmic rays coming from place.
Do you believe in Urine therapy? In other words you should drink your own urine.
Ohh!! For me it is a terrible but there are many practitioners were performing this kind of therapy.
By gathering urine, particularly in the morning, practitioners stated that they are able to get the most benefits from this practice. It is stated that it can treat approximately all sicknesses, as well as the ordinary cold and AIDS. By affecting on a person’s pate each day, it can even help produced back the falling hair.
Medical practitioners stated that some of the rudiments present in urine could have useful factors, there are, nonetheless enhanced and more pleasant alternatives for taking in these rudiments. Vitamins, for example are wash out out with the urine when taken in excess.
Supposedly, this vitamin carrying urine could be ingested and processed once more by the body. But there are more capable habits to get one’s day by day dose of vitamins; this is through a balanced diet.
Nickel, an easily shaped and polished metal, derives its name from 'Old Nick', meaning the Devil. Copper miners in Germany found ores that they could not reduce to workable copper and they called these copper-like ores Kupfernickel meaning 'devils copper'. The unknown substance causing the trouble was actually another element, now known simply as nickel.
A Soviet power station started working in 1954. But the first nuclear plant to generate electricity for domestic use was Calder Hall in Britain which was opened in 1956.
The world's biggest raindrop was measured over Hawaii in 1979.
It was 8 millimetres in diameter.
Halley's comet has an orbit around the sun that brings it closer to Earth every 75 to 76 years.
Since Edmund Halley saw it in 1682, it has returned in 1758, 1835, 1910 and 1986. It should be back again in 2062.
Scientist applies the Myr to measure geological time. One Myr is equal to 1 million years ago. The Earth was born in 4500 Myr.
Burning or Combustion is a chemical reaction between a substance and the oxygen in the air. Heat is given off and flame may be seen. Burning cannot occur without oxygen.
When water freeze up to ice, it increase. Rainwater collecting in a splintered rock will enlarge when frozen, and the ice pressing against the crack can split off a piece.
The Chinese were able to dig out oil from below the ground 2000 years ago. But the first modern oil well was drilled in Pennsylvania, USA in 1859. The Pioneer driller was Edwin L. Drake, who bored through 21 meters of rock to strike oil. This was 30 years before the development of the petrol-engine car. The drillers then were mainly interested in extracting kerosene, which was burned in oil lamps.
Rubber stretches because it is composed of long chains of molecules or polymers. These molecules slide easily over one another allowing the rubber its shape with ease.
The amygdala marked as uh-MIG-duh-luh. This almond-formed and dimension section of the brain assists us to choose whether to brawl, take escape or simply be frightened. Scientists considered the amygdale which it helps form long-term memories, especially those joined to a toughed emotion.
The most common element in the Earth’s crust is oxygen (about 50% by weight). Next comes silicon, (about 28% by weight).
