My Science School

The first aero plane ever to fly was built by a French naval officer, Felix du Temple de la Croix. In 1874 his monoplane, powered with a hot-air engine, took off from the top of a hill near Brest in France. It did not get far, just a short hop, but it was a beginning. A few years later, in 1890, Clement Ader of France flew his own plane, Eole, entirely under its own power for about 50 meters. It was a world record.

     The first truly successful aero plane flight was in 1903. In December of that year Orville Wright flew his chain-driven plane Flyer I at a speed of 8m.p.h and at an altitude of 12 feet for 12 seconds in North Carolina, United States. It was several years before the Wrights’ achievements were fully appreciated in America.

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Wood becomes waterlogged when all its cells are filled with water. It can absorb water only up to about 30% its own weight. As it does so, the wood swells until it reaches “fibre saturation point” or its maximum volume.

     If further water is added, it will penetrate to the cavities of the cells, but no further swelling will take place. Waterlogged wood no longer floats because the air spaces within are filled with fluid making it too heavy.

    The word “waterlogged” is used to describe ships that have been flooded and sunk, or meadows and fields that are so wet that they must be drained before they are any use for growing food.

    A meadow becomes waterlogged in the same way as wood. The land can no longer absorb more water or drain it away. Many areas of land remain permanently in this condition unless they are reclaimed for farming.

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Stainless steel resists rust because it contains a high proportion of chromium to carbon. Before the arrival of this alloy just before the First World War, Knives and other household articles made of steel easily rusted unless very carefully dried.

    It was an English researcher named Harry Brearley who discovered that rust was encouraged by the carbon in steel and other metals. The less carbon and the more chromium in steel, the better it would resist rust.

      But a careful balance had to be struck. Completely carbon-free steel was impossible to make, and only a limited amount of chromium could be included, because it tended to make steel brittle. Brearley discovered a satisfactionary formula only after many experiments.

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Felix Wankel, a German motor engineer, invented the rotary piston engine which bears his name. Deprived of a university education when his family’s fortune vanished in the German inflation of 1919-20, he went in for car repairing and set up his own business in 1924 at the age of 22.

        Soon he began work at designing a rotary piston engine, an idea which had attracted engineers since the invention of the stream engine. From 1934 to 1936 his research was backed by B.M.W. and from 1936 to 1945 by the German air force. In 1951 he established his own research institute and financed it by working as a consultant.

Wankel succeeded in discovering the secret of effective seals between the rotating pistons and the casing. He also discovered the geometrical form of an engine that could carry out the four-stroke cycle in one chamber without valves, giving a useful high compression ratio. His engine ran successfully for the first February, 1957. N.S.U. began limited production of Wankel engines for a car is 1963, and went into large-scale production in 1967.

      The rotary piston engine challenges the usual internal combustion engine, using reciprocating pistons, because it offers reduced size, weight, vibration, noise and production costs for comparable thermal efficiency. It is considered suitable for industrial, marine and aeronautical uses.

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An automobile is driven by an internal combustion engine which will work properly only if the right amounts of petrol and air are mixed together. The carburetor is the part of the engine where the mixing takes place.

     The burning of fuel in the engine is a chemical reaction in which petrol combines with the oxygen of the air to produce water, heat energy and oxides of carbon. A chemically correct mixture should have 15 parts of air to one part of petrol, both by weight. The amount of air then present is just sufficient to burn the petrol completely. If the engine uses a mixture with an excess of petrol a rich mixture-a small amount of unburnt petrol will be present in the exhaust fumes.

     A carburetor has to produce the required mixture to suit different engine conditions, such as starting, idling, acceleration, cruising and application of full power. It must be able to pass the correct mixture at all engine speeds and under varying loads, and has to atomize the petrol into tiny droplets and vaporize the resulting spray a combustible mixture.

     Inside the carburetor is a throttle valve which can increases or decreases the amount of mixture passing into the cylinders, which in turn control the power of the engine. This valve is mounted on a spindle which is operated by the accelerator pedal.

    A special device called a “strangler” or choke is also incorporated to help in starting the engine in cold weather by allowing an extra-rich mixture.

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A plastic, in the modern sense of the word, is a synthetic or man-made material which can be formed into various shapes. The first plastic material was Celluloid, made in 1868 by an American, John W. Hyatt, by dissolving nitrocellulose under pressure.

      The use of plastic began slowly, but shortages of natural material caused by two world wars forced scientists to develop substitutes. Since the Second World War the making of plastics has become a gigantic industry, which has grown so fast that many people still have only a hazy idea what plastics are. In fact, the term “plastics” is as general as the word “metals”. The high-temperature cone of a rocket and the highly inflammable table-tennis ball are both plastics, just as lead and steel are both metals.

    However, all plastics have some things in common: first, they are entirely man-made and not found in nature; secondly, they consist of large molecules of an organic nature; thirdly, at some stage in their manufacture they are liquid and can be shaped; and fourthly, in their final state they are solid.

    Most of the raw materials for plastics are produced by the petroleum and coal industries. Scientists are able to produce different properties in plastics so that they can be used in a tremendous variety of articles.

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A car uses overdrive when it is travelling at high speed over long distances. Overdrive, or cruising gear, is a device which enables the engine to run at a relatively low speed even when the vehicle is travelling fast.

   All internal combustion engines fitted in vehicles need some kind of gearbox because their efficiency at low speeds is poor. The use of different gears enables the speed of the engine to be harmonized with that of the car. The gears may be engaged or shifted by hand or operated by an automatic gearbox.

    Most cars have a four-speed gearbox. The driver uses first gear for starting and changes to second and third gears as the car gains speed. Finally in top of fourth gear the engine speed is transmitted unreduced through the gearbox. In overdrive a large gear wheel drives a smaller gear wheel on the propeller shaft. This shaft then rotates faster than the engine, thus reducing wear and tear and saving petrol.

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Clyde Tombaugh, a young American research student, made the last discovery of a planet while working in 1930 at the Lowell Observatory, Arizona state College. This planet is Pluto, the ninth one in order of distance from the sun, 3,670 million miles away.

    Although Tombaugh, who was 26 at the time, was the first astronomer to see Pluto, its existence had been suspected by Percival Lowell, builder of the observatory at Flagstaff, Arizona. Lowell began searching for the planet in 1905, the year before Tombaugh was born. He observed that there was a difference between the predicted and actual positions of Uranus, and this led him to conclude that there must be another planet. His final calculations about “panel X” were published in 1914, but he had still not found the planet when he died two years later.

    Another American, W.H Pickering, took up the search, concentrating on the irregular movements of the planet Neptune. He saw a clue in the movement of comets, which seem to be attracted by large planets. Here were 16 known comets whose paths took them millions of miles beyond Neptune. Which is 2,800 million miles from the sun, and Pickering was convinced that they were being attracted by a still more distant planet.

   In 1919 yet another hunt was begun by Milton Humason at Mount Wilson Observatory, Pasadena, California. Instead of mathematical calculation, Humason tried photograph. He took two pictures of a series of stretches of the sky, with a gap of one or two days between exposures. In such photographs stars stay still, but planets change position.

    When Tombaugh discovered Pluto, it became clear that Humason had photographed the planet twice. Once it had been masked by a star, and the second time its image had coincided with a flaw in the photographic plate. The main difficulty in the search had been that Pluto was extraordinarily faint. Pickering formed the opinion that it was not Lowell’s planet X, but that a huge planet remains to be discovered.

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The first mountains and valleys were the crust formed as a result of the cooling of the molten mass of the earth. As the planet contracted the crust twisted and cracked, forming new mountains.

      Mountains are still being formed by volcanic eruption. A crack is the earth’s crust allows molten rock and ash to be forced out, forming a cone-shaped mountain growing as it continues to erupt.

    Fault-mountains are formed when the earth’s crust cracks, or faults, under pressure from inside, and one side of the break is pushed up against the other to form a cliff.

    The highest mountains are in the Himalayas where some are over 25,000 feet. Only in the Rocky Mountains and in the Andes are there any others over 20,000 feet.

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A space suit enables an astronaut to survive by providing him artificially with conditions like those he is used to on earth.

    These conditions can be reproduced in a large space craft or space station in orbit, but an astronaut still needs a space suit for operations outside the craft or for an emergency.

     In space men lack the air needed for breathing, the pressure required to stop their blood from boiling and the natural protection of the atmosphere against radiation. All these must be supplied by the space suit which also must withstand the cold of space.

     When an astronaut ventures into space, he leaves behind the safety of the atmospheric blanket which we, on earth, take for granted. His space suit becomes his own personal little world.

 

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Litmus paper turns red when placed in an acid solution, but blue is the solution is alkaline. This absorbent paper is the oldest and most commonly used indicator of the presence or absence of acid. Its special qualities are due to the fact that it has been soaked and impregnated with a mixture of dyes called litmus.

        The litmus mixture was originally produced by the action of air, ammonia and an alkali carbonate on certain lichens found in the Netherlands. It is now made from azolitmin and erythrolitmin.

     A litmus solution is sometimes used. But the message is the same. A few drops added to a liquid turn it red if it is acid and blue if it is alkaline.

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A detergent is substances which has a power to cleanse. This description applies to soap, as well as to soap, as well as to soapless shampoos and washing powders. A detergent usually has surface activating properties, which means that it is able to reduce the surface tension of water.

      In the process of cleaning the detergent acts as a bridge between the solid matter and the water. Soap molecules are shaped like tadpoles. The head is soluble, but the rod-like body is composed of an insoluble fatty substance. When mixed with water part of the soap tries to get away and the rest stays, thus breaking down the water’s surface tension. There is not sufficient room for all the soap molecules on the surface of the water. So they form bundles with the water-resisting rods on the inside. The dirt attracts the fatty part of the soap molecules which lift and surround it, while the soluble part of the molecules lifts and rinses the dirt away.

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Nowhere- it simply changes into other substances. That is what burning does to everything.

       The moment you put a match to the wick, you start a change in the candle by turning the solid wax into a liquid. The liquid wax rises to the wick by an irresistible process called capillarity, the simplest example of which is the way blotting paper soaks up ink or water. Then the liquid wax changes into a gas which burns-a chemical reaction which releases energy in the form of light and heat.

     The presence of the gas can be demonstrated by blowing out the candle and immediately holding a lighted match an inch or so above the wick. The inflammable vapour instantly catches fire and the candle lights up again without the match having actually touched the wick.

     Other changes are taking place while the candle burns. The wax is a complex chemical compound of carbon and hydrogen. The process of burning is simply the combination of the wax with the oxygen in the air. If you put a jar over the candle, it will quickly use up the oxygen and go out.

Suring the time the candle burns, the carbon joins with the oxygen in the air and makes carbon monoxide and carbon dioxide, and the hydrogen combines with the oxygen to produce water.

    While all these changes in the substance of the candle are taking place, the candle, of course, is becoming shorter. But it is not “going” anywhere. Its materials are simply changing into other substances.

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A sheet of paper consists of vegetable fibers of different sizes, twisted and intertwined with each other and finally squeezed together to make a sheet with a surface smooth enough to write or print on.

        Originally it was discovered that if a mixture of wood pulp and water was spread on a sieve, the water would drain away and leave a deposit which, when dry, could be peeled off as a sheet of paper.

Although the Chinese had been using paper since A.D. 105 it was not introduced into Europe until the 15th century. The raw materials used for modern hand-made paper are cotton and linen rags. Such paper is very expensive to produce.

     Machine-made paper is processed in paper mills from esparto grass, wood and straw, and is much cheaper. The materials for both types of paper-making have to be put through the same basic procedure of repeated washing and bleaching to get rid of impurities.

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Glass fiber is a mass of very fine strands of glass. When ordinary glass is spun into thin threads it is strong and bendable, unlike normal glass objects, which are brittle and break easily.

       These silky strands of glass can be woven into a material or massed together like cotton-wool. Glass fiber does not decay or corrode. It is a good insulator and a poor conductor of electricity. Curtains made of this material do not rot in damp conditions or in sunlight. Now that technical dyeing problems have been overcome, glass Fiber can be patterned.

    Many plastics tend to crack or bend under stress or impact, but  combining them with strands of glass fiber results in very light, strong and useful materials. Glass fibre increases their strength in much the same way as concrete is reinforced with steel rods. These mixtures are moulded to make such things as aircraft parts, car bodies mats of glass fiber are used for filters and washers, and blankets of the material provide good in solution for houses.

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