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# Biomechanics

### Functional Anatomy

Term | Definition |
---|---|

3 forces acting on the body at all times | 1. Gravity; 2. Ground reaction forces; 3. Muscular forces |

impulse-momentum relationship | the effect of a force over an interval of time |

scalars | described by magnitude only |

vectors | have a magnitude & a direction |

vector resolution | operation that replaces a single vector w/ 2 perpendicular vectors |

biomechanics | application of the laws, concepts, & tools of physics & engineering to various aspects of human motion; the how & the why of how we move |

kinematics | the study of bodies in motion with respect to space & time, without regard to the cause of the motion or the forces involved in the motion |

establishing an origin | usually at ground level, in a convenient location w/ respect to the motion studied, or at the center or corner of a force plate |

moment | a tendency for rotation; aka torque; indicates stress at joints |

linear displacement | change in position; direct distance from initial to final; a vector; net effect of motion |

linear distance | scalar value; length of the path |

velocity | vector; rate of change in position; how fast & in which direction is the movement occurring; displacement/time |

speed | scalar; how fast an object moves; distance/time |

acceleration | rate of change in linear velocity; change in velocity/change in time; measured in units of m/s^2 |

angular motion | all parts of a body move through the same angle; same velocity, but each part of object is moving at a different speed. |

angular distance | the sum of all angular changes undergone by a rotating body |

angular velocity | the rate of change in angular position; angular displacement/time; measured in units of degrees or radians. |

angular acceleration | the rate of change in angular velocity; change in angular velocity/time; measured in units of degrees/sec or radians/sec |

kinetics | the how & the why behind a motion; the study of the forces that produce a motion |

impulse | force applied over time; =Ft (units N/s) |

torque | T= fd (product of F & the perpendicular distance from the F's line of acton to the axis); the angular equivalent of force; moment of force |

center of mass | point at which the sum of torques= 0 |

stress | Force/unit of area over which the force acts |

law of inertia | an object at rest will stay at rest unless acted upon by an external force |

law of acceleration | F= ma (mass x gravity) |

law of reaction | for every action, there is an equal & opposite reaction |

inertia | a body's resistance to linear mass |

moment of inertia | a body's resistance to a change in angular motion; I= m (mass) x r^2 (radius^2) |

angular law of acceleration | torque; T= I (moment of inertia) x a (angular acceleration) |