click below

click below

Normal Size Small Size show me how

# Gravity

### Introductory Concepts

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

“G” | The “universal gravitational constant” = 6.67 X 10^-11 N-m^2/kg^2 |

Direction – horizontal | Perpendicular to the direction gravity acts |

Direction – vertical | The line the direction of gravity acts |

Newton’s Law of Gravity | The description of the force acting between any two objects in the universe; Depends on the inverse of distance-squared |

Projectile | An object moving under the influence of gravity but in two dimensions (horizontally and vertically) |

Projectile | The horizontal and vertical motions are totally independent of each other |

Projectile – Horizontal | No force acts in horizontal direction; therefore the horizontal direction has constant velocity |

Projectile – vertical | The force acting in the vertical is gravity; the acceleration is g = 9.8 m/sec^2 (usually taken as 10 m/sec^2 in problems) |

Satellite | An object moving around a planet, like earth satellites and the moon |

Satellite – behavior | Is free-falling; due to “horizontal” or “tangential” velocity, it “falls around” the planet; constant energy |

Speed - escape | the speed necessary for an object to possess in order to completely leave the planet; 11.2 km/sec for earth |

Speed – orbital | the tangential speed necessary for an object to become a satellite just above the atmosphere of a planet; 8 km/sec for earth |

Support force | The force necessary to exactly oppose the gravitational force on an object resulting in equilibrium |

Weight | The support force opposing the attractive force of the earth on an object due to gravity |

Weightless | No support force; results in free-fall |