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The Wright Sister

When you think of airplanes, you may think of Wilbur and Orville Wright. Their early experiments led to the first manned airplane flight 100 years ago. There's another member of the Wright family, however, who also played an important role in the airplane industry. Katharine Wright isn't as well known as her brothers, but her work helped make ...

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TheWrightSister
Biology

Throw Out Your Thermometer

If you're out camping, and you've left your favorite thermometer at home, how can you figure out the temperature? Not the most earth-shaking problem, we admit, but there is an all natural way to find ... Continue reading

Thermometer
Engineering

High Altitude

Have you ever read the directions on a box of cake mix? There are special instructions for high-altitude baking. Has anyone who visited the Rocky Mountains told you how hard it was to breathe there? ... Continue reading

HighAltitude
Astronomy

The Constellations

The random arrangement of the stars visible to the naked eye has remained essentially unchanged since the time of the first written records. One of the earliest complete lists we have was compiled in ... Continue reading

TheConstellations
Chemistry

Uses Of Hydrocarbons

The hydrocarbons are the most broadly used organic compounds known, and are quite literally the driving force of western civilization. The greatest amounts of hydrocarbons are used as fuel for ... Continue reading

UsesOfHydrocarbons

Get the Point?

DiscusJavelinThe discus and javelin first appeared in ancient game competitions in 708 B.C. Javelin events included both target throwing and distance throwing using a sling. By 1780, the javelin was adopted as an event by the Scandinavians, and the current one-handed throwing style while running was adopted at this time. In 1953, a hollow javelin was developed in the United States by Franklin 'Bud' Held who also set a new world record. Since the javelin had a standard weight, the surface area was increased which augmented the javelin's flight capability and caused it to land horizontally. In 1966, the javelin was thrown over 100 meters (328 feet) by an athlete using a discus style turn before the throw. This throwing style was judged unsafe and thereafter banned by the International Amateur Athletic Federation (IAAF). The 100-meter mark was broken again in 1984. Subsequently, the IAAF adopted new rules to ensure shorter flight times and sport safety.

The modern javelin is designed with the center of pressure located behind the center of gravity. This generates a nose down pitching moment (the tendency to produce motion about a point or axis), which reduces the javelin's flight time. Although the center of pressure's location varies during the javelin's flight, it always remains behind the center of gravity. As a result, the nose of the javelin pitches down. This nose down orientation also guarantees that the javelin lands point first. A point first landing ensures a safer event. In addition, since the javelin can no longer slide across the ground, the distance can be measured with greater accuracy.

During flight, the javelin also spins about its longitudinal axis. At a rate as high as 25 revolutions per second, the spin stabilizes the javelin in flight. The javelin also experiences oscillation down its length during flight. Oscillation is detrimental to the flight and needs to be minimized by the thrower or by the materials used in the javelin. Modern javelins are made from steel, aluminum or aluminum alloy. Novice throwers use a less stiff javelin (which is more forgiving in training). As skill is developed, a stiffer javelin is used (straighter flight). The steel javelins are the stiffest and have less vibration than the aluminum models, while aluminum offers flexibility and may be easier to throw.