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Law of conservation of angular momentum...

Law of conservation of angular momentum

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Principle or law of conservation of angular momentum : The angular momentum of a body is conserved if the resultant external torque acting on the body is zero.
Explanation, Consider a person holding weights and seated on a platform that can rotate freely about a vertical axis. Let the platform be set into rotation at an angular speed o, with the person's arms and the weights close to the body. On extending out the arms horizontally, the moment of inertia of the system increases from `I_(1)" to "I_(2)` because the weights are now farther away from the axis of rotation. Since the angular momentum is conserved, `I_(1)omega_(1)=I_(2)omega_(2)` so that the final angular speed, `omega_(2)=omega_(1) ((I_(1)/_(2))` Because `I_(2)gt I_(1), omega_(2) lt omega_(1)` Hence, the rotation slows down.
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  1. Law of conservation of angular momentum

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