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Human Sling Shot

 

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Overview
Life is full of ups and downs. Sometimes, though, moving between these extremes can be quite entertaining. Just check out the human slingshot-or ejector seat-ride. The ejector seat ride has its roots in bungee jumping. Both depend on the elasticity of bungee cords to provide a force. In bungee jumping, the elastic force is used to negatively accelerate (decelerate) and halt a jumper's body as it plummets toward the ground. The ejector seat works in reverse. Elasticity overcomes gravity by yanking upward and positively accelerating (propelling) the riders sky-high. Riders are strapped into a cage that has been pulled down to the ground, stretching the bungee cords connected high above to maximize potential energy. Then the entire unit is released skyward, converting the potential energy of the bungee cords into the kinetic energy of the riders, shooting them 45 meters (150 feet) into the air. At the moment of release, the rider feels the maximum acceleration. Of course, energy is dissipated with each pass as heat is generated by friction between the bungee cords and air and within the cords themselves. The g-forces caused by the bungee acceleration are the very same forces that affect race car drivers and astronauts. Even when we're just standing around, our bodies experience the force of 1g, as gravity pulls our bodies toward the center of Earth. On the ejector seat, force due to the ride alone may be up to 2g, but the force your body feels is actually 3g, once you add in gravity as well. The sudden shifting of your body's position upsets the fluid in your inner ear, affecting your sense of balance and triggering responses such as an increased heart rate and tightening of your stomach muscles. Your body seems incredibly heavy as g-forces push you and the blood in your body back in the direction you started from. Your heart works harder to get the oxygen- and nutrient-bearing blood back to the brain and overworked stomach muscles. This creates a temporary chemical imbalance resulting in faintness or queasiness. At the moment acceleration stops and the bungee cords stop pulling on you, the only force from then on is gravity-you actually experience free fall. Somehow, your body adapts and often you even enjoy the experience.

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