Physics Of Angular Momentum Project

1044 Words5 Pages
Kathleen Murphy
Physics of Angular Momentum Project
Angular Momentum: The Physics of Spinning
Although many know the physics of “spinning”, not many people are aware of how angular momentum explains the physics of rotation. Now it is true that all objects have a momentum, a product of mass and velocity. But similarly, the inertia of rotating objects is called angular momentum. When a direction is given to a rotational speed, we call this rotational velocity, and its vector is rotational speed. Therefore, angular momentum is the product of rotational inertia and rotational velocity, or L=Iw. This equation can be used in physics to find the angular momentum of an extended object, with the I being the inertia (kg x m2) the
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An example of this would be a man with his arms extended, holding weights. If his arms are extended with weights on the end, his overall rotational inertia is relatively large and as he turns, his angular momentum is the product of his rotational inertia and rotational velocity. If he pulls the weights in, his rotational inertia is decreased, but his rotational speed increases. This concedes the idea of the law, that the smaller one part is, the larger the other part must be. There are examples in sports too, like cheerleading. When a flyer in cheerleading is thrown and is going into her rotation, she isn’t at her fastest motion yet, but her ability to resist a change in motion is quite high. This ability to resist a change in motion is her inertia, which in our case, is mass multiplied by radius squared. So while she has arms and legs extended before she fully rotates, she has less speed, but a longer radius that allows her inertia to remain larger. When she is fully into the rotation with legs and arms fully tucked in, she has a smaller radius, but because of the conservation of momentum, this loss of inertia must be made up in speed. So while the flyer is doing the hardest part of her trick, the real rotation, her body is moving the fastest so that her lack of inertia can not affect the success of her move.
Now my final example is the figure skater, how do we explain mathematically why when her arms are extended she goes slower and when her arms are pulled in she
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