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# OAT Physics

### Chapter 3 - Work, E, and Momentum

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

Work | F acting on an object which moves through a distance d; = Fd cos theta |

When F and d are perpendicular | No work is done cuz cos 90 = 0 |

Power | rate at which work is done; Watts = J/s |

Kinetic E | E of motion; = 1/2 mv^2 |

Potential E | E of position; = mgh |

When mechanical E is not conserved... | E is drained away in form of heat |

Mechanical E | KE + PE = total E |

W when is comes to mass and velocity | = change in KE |

Non-conservative Force | friction |

Conservation of E | when the work done by non-conservative forces is zero (no air resistance), E is conserved and E = KE + PE |

Pulleys | these allow F to be reduced but distance that the force is exerted over is increased to compensate |

Efficiency (Pulley) | W out/W in ; load x load distance/effort x effort distance |

effort distance | load distance multiplied by the number of pulleys present |

Momentum | p = mv |

Impulse | J = Ft = change in momentum |

Conservation of Momentum (collisions) | Total p initial = Total p final; (p of object a)(p of object b)i = (pa)(pb)f |

Completely inelastic collisions | objects stick together after the collision; only momentum conserved |

Completely elastic collisions | objects dnt stick together after collision; KE is conserved; use momentum AND KE equations here |

Center of Mass Equation | X = (m1x1 + m2x2) / m1 +m2; x is the center point of the object. If a cube has a length of 4m, x would be at 2m |