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# Gullett-Phys-Ch7-8

### Physics-Ch7-8-Energy and Circular Motion

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

work | the product of the force and the distance moved by the force |

power | the time rate of work |

work formula | W = Fd (force times distance) |

power formula | Power = work done / time interval |

energy | the property of a system that enables it to do work |

mechanical energy | energy due to the position of something or the movement of something |

potential energy | energy that something possesses because of its position, a type of mechanical energy |

kinetic energy | energy that something possesses because of its motion, a type of mechanical energy |

work-energy theorem | the work done on an object equals the change in the kinetic energy of the object |

law of conservation of energy | energy cannot be created or destroyed; it may be transformed from one form to another, but the total amount of energy never changes |

machine | a device, such as a lever or pully, that increases (or decreases) a force or simply changes the direction of a force |

conservation of energy | the work output of any machine cannot exceed the work input |

lever | a simple machine consisting of a rigid rod pivoted at a fixed point called the fulcrum |

efficiency | the percentage of the work put into a machine that is converted into useful work output |

tangential speed | the linear speed tanget to a curved path, such as in circular motion |

rotational speed | the number of rotations or revolutions per unit of time |

rotational inertia | the property of an object to reisist any change in its state of rotation; if a rest, the boyd tends to remain at rest; if rotating it tends to remain rotating and will continue to do so unless acted on by an external net torque |

torque | the product of force and lever-arm distance, which tends to produce or change rotation: |

torque formula | torque = lever arm x force |

center of mass | the average position of the mass of an object, it moves as if all the external forces acted at this point |

center of gravity | the average position of weight or the single point associated with an object where the force of gravity can be considered to act |

equilibrium | the state of an object in which it is not acted upon by a net force or net torque |

centripetal force | a force directed toward a fixed point, usually the cause of circular motion |

centripetal force formula | F - mv^2 / r |

centrifugal force | an outaward force apparent in a rotating frame of reference. It is apparent (ficticious) in the sense that it is not part of an interaction but is a result of rotation |

linear motion | the product of the mass of an object and its linear velocity |

angular momentum | the product of the mass of a object and its linear velocity |

conservation of angular momentum | when no external torque acts on an object or a system of objects, no change of angular momentum can occur. |