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Show Sunday Science Soap by Dr. Robert FiBinni R. Highways Kadesch A tX STATE ROAD Commission had a real problem on its hands. The villages ol Xenon, Yardley and Zimmer had been promised a new road that would connect the three towns. The commission was low on funds as usual, and was anxious to build the road for the least possible cost. This meant finding the shortest possible route to keep costs down. The three towns formed a triangle, and a road from Xenon to Yard-ley- , and another fro mYardley to Zimmer, would surely do the job. But the chief of the road commission suspected that there was a better way. After giving the problem some thought, he put his assistants to work on the problem. Next morning one of the road designers came to work with some soap bubble solution and two clear plastic sheets. He solved the entire road problem in less than three minutes. Shortest posible "road" joins Xenon, Yardley and Zimmer. When four "towns" are involved, this And five "towns" gives is soap film network. soap bubble engineers this pattern. SOLVE YOUR own road building problems. In addition to the soap solution you will need a small clear plastic box. Bobby pins are sometimes sold in plastic boxes about two by three inches in size. Certain drug products are packed in them also. Ask your pharmacist. Another possibility is to use clear plastic sandwich boxes. Straight pins are often sold in small hexagonal plastic boxes with a clear plastic lid. Saw or file away the sides of the box with the exception of the hinges and snap fasteners on the front. The object is to leave the top and bottom of the box with as little else as possible. Now drill five very small holes through the top of the box and five more in the bottom of the box directly beneath the holes above. These should be placed irregularly but somewhat near an oval or a circle almost as large as the top of the box. Now insert small finishing nails or heavy brass wire through three of the pairs of holes. SUBMERGE entire box with its nails in the soap bubble solution. This will completely wet the inside. Blow out any films that may be produced. Now form films that extend from nail to nail by first moistening a flattened soda straw with the soap solution. Touch the straw along the bottom of the box and to the two nails, and move the straw up to the top of the box. With a little practice, this technique will leave a sheet of soap solution which extends between the two nails and the top and bottom of the box. REPEAT this procedure to connect a film between the third nail and the center of the film already suspended between the first two nails. The soapy film will slide into a position that makes three straight films, one from each nail, which meet at a point Inside the triangular arrangement of nails. The nails represent the villages of Xenon, Yardley and Zimmer. The lines along which the connecting soap films meet the box give the path for the shortest possible road to connect the three. The stretchy soap film slides freely across the top and bottom of the box and pulls as if it were rubber to make Itself as short as possible. It is this property of the soap films that enables its position to give the right answer to the road building problem. SOMETIMES the shortest road connecting three towns consists of only two straight stretches of highway. This will be true when the triangle formed by the three towns has one angle which is greater than a third of a full circle, or 120 degrees. If all the angles are less than 120 degrees, the shortest road system is the kind that has three sections meeting at a point inside the triangle. This road building problem can also be solved mathematically, but it is a rather advanced problem in geometry. The soap films solve the problem accurately and with beauty and in far less time. Occasionally two films will join to different portions of the nail to make only two films when there should be three. When this happens, merely stroke the nail with the moistened straw. , INSERT a fourth nail, or town, between the top and bottom of the box. Form the soap films between the nails as before to find the shortest possible road which will connect all four towns. Do the same for a fifth town. Notice particularly that at those points where three soap films meet, the angles between the films are always 120 degrees. The road system usually forms a honeycomb network connecting the towns. Profiles in science The Wright Brothers: The first powered flight by Patrick and Getz The FIRST MAN to fly was Daedalus. Thats the version of Greek mytholgy. The myth says Daedalus and his son flew from Crete to Greece after fixing wings to their shoulders with wax. The son ignored Daedalus advice, flew too near the sun. The heat melted the wax and Icarus fell to his death in the sea. Despite the simplicity of Daedalus' idea, the airplane is not just one invention. It is a combination of many ideas and inventions the idea of the lifting power of inclined planes, the pulling and pushing power of propellers, jets and rockets, the control of height and direction by adjustment of the angles of surfaces. and his brother, WILBUR WRIGHT are the real inventors of the Orville r flying machine. In 1890 the brothers were putting out a newspaper and running a bicycle shop on the side. The work of the great German glider expert, Otto Lilien-thal- , interested them in flight. At first it was a sport, but soon they gave up (1867-1912- ) (1871-1948- heavier-than-ai- 16 everything else for the hobby" that brought them the homage of kings and presidents. Lilienthal balanced his gliders with his own weight, but when he was killed in a crash in 1896, the Wrights were sure that some other method of balancing was needed. There followed their first invention that Of adjustable wing and tail surface fixed to a glider with a definite center of gravity. In 1901 they built the first wind tunnel. In 1902 they built the first successful power-driveflying machine, their wind tunnel experiments having shown them how it could be n done. THIS MACHINE weighed 750 pounds, including the weight of the pilot, and had 12 horsepower. Wilbur Wright made four flights in it at Kitty Hawk, N.C., in 1903, the longest lasting 59 seconds. In 1905 they had improved surfaces to avoid tailspin, and Wilbur flew 38 minutes.. In 1908 they flew an hour and 15 minutes, and some visionary" in the War Department saw possible wartime use for the Wright machine. They got their first government contract in 1909. Orville, left, and Wilbur Wright World Wars I and n and the Cold War have done the Job of changing the original Wright machines into modem rocket and space ships. Reading: Flight Into History, by E. E. Frueden-tha"The Wright Brothers, by Fred Kelly. l, The Salt Lake Tribune Home Magazine |