|MadSci Network: Physics|
Think of the bow as being made up of a bunch of linked pieces. Each of these pieces behaves like a spring, storing energy as one stretches it. Just like in a spring, the further you pull back on the bow, the more energy you store. When the bow is in the "relaxed" state, there is no stored energy. As you pull back on the bow, part of it (let's assume the inner wall) does not want to be compressed and so maintains it's relaxed length. The only way the for the bow to be bent is if the outer wall stretches. This stretching is storing the energy. In a material, this stored energy is called "stress" and is measured as a force per unit area in the direction of the force. In the US, it's common to measure it in pounds per square inch; the metric equivalent would be Newtons per square meter. Christopher M. Seaman Alcoa Technical Center
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