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# Biomechanics

### Angular Kinetics

Question | Answer |
---|---|

Angle equivalent to mass? | Moment of Inertia |

Angular analogue to mass / inertia | Moment of Inertia |

what does it have resistance to? | angular acceleration |

what might affect a rotating object? | Distance of mass to the axis of rotation |

EX of distance of mass to the axis of rotation | swing straight arm vs swing bent arm |

Moment of inertia | n I= ∑ m x d^2 i=1 |

Which axis is it easier to rotate the forearm? | Longitudinal axis, supination/pronation |

Values characterized by using the formula | I = m x k^2 |

Radius of gyration (k) | represents the objects mass distribution with respect to a axis of rotation |

About which axis is the moment of inertia the smallest? | Longitudinal - arms down |

Angular momentum | H = I x ω = (mk^2) x ω |

Conservation of angular momentum | will remain constant as long as there is no external torque(s) |

If gravity is the ONLY external force and there is NO external torque | Angular momentum is conserved |

Is angular momentum a vector? | yes |

when a body is on the air, if the angular momentum of one body part is increased | then all or part of the rest of the body must experience a decrease in angular momentum |

while on the air angular momentum is conserved | but it can be transferred |

Angular impulse | (I x ω)Before + ΣT∆t = (I x ω)After |

Angular impulse | ΣT∆t |

1st law of angular motion | A rotating body will maintain a state of constant angular motion unless acted upon by some net external torque |

2nd law of angular motion | A net external torque produces angular acceleration of a body that is directly proportional to the magnitude of the net torque, in the same direction as the net torque, and inversely proportional to the body’s moment of inertia (ΣT = I⍺) |

3rd law of angular motion | For every torque exerted by one body on another, there is an equal and opposite torque exerted by the second body on the first |