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# Physics Units 1 & 2

### Newtons Laws

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

scientific method | Principles & procedures for the systematic pursuit of knowledge; recognition of a puzzle, collection of data through observation & experiment, & the formulation & testing of hypotheses |

scientific attitude | The scientific method inclined toward inquiry, integrity, & humility; a willingness to admit error |

hypothesis | An educated guess, not fully accepted as factual until tested over & over again by experiment; must be testable & able to be shown wrong |

law | A hypothesis that has been tested over & over again & has not been contradicted; also a principle |

fact | A statement about the world that competent observers who have made a series of observations agree on |

scientific theory | A synthesis of a large body of information that encompasses well-tested & verified hypotheses about aspects of the natural world; not fixed, they undergo changes |

speed | How fast an object moves; the distance traveled per unit of time; speed=distance/time |

velocity | An object's speed AND direction of motion; a vector quantity |

acceleration | The rate at which velocity changes with time; the change in velocity may be in magnitude, direction, or both; acceleration=change in velocity/time interval |

free fall | Motion under the influence of gravity ONLY; free fall acceleration=10m/s^2 (does not depend on a object's mass) |

non free fall | The force of air drag experienced by an object; depends on the frontal area of the object & the speed of the falling object |

Newton's First Law | An object continues in a state of rest OR of uniform speed in a straight line unless acted upon by a nonzero force; the property of things to RESIST changes in motion |

force | A push or pull; measured in newtons or pounds |

net force | The vector sum of forces that act on an object; more than a single force |

scalar quantity | A quantity that has ONLY a magnitude; mass, volume, speed |

vector quantity | A quantity that has BOTH magnitude & direction; force, velocity, acceleration |

vector | An arrow drawn to scale used to represent a vector quantity (gives direction) |

resultant | The sum of two or more vectors; for a parallelogram: R=Sq root of x^2 + y^2 |

tension | A stretching force |

mechanical equilibrium | The net force on an object is zero- undergoing NO change in motion; if at rest, will stay at rest |

dynamic equilibrium | The net force on an object is zero- undergoing NO change in motion; if in motion, will stay in motion |

equilibrium rule | The vector sum of forces will always equal zero |

normal/support force | An upward force exerted on an object |

friction | The resistive force that opposes the motion or attempted motion of an object with which it's in contact or through fluid; always in the opposing direction; sliding friction (fluid) depends on speed |

mass | The quantity of matter in an object; the measure of inertia of an object or its resistance to change motion- the more mass, the more inertia; is directly proportional to weight |

weight | The force upon an object due to gravity (mg); directly proportional to mass- if mass doubles, weight doubles |

volume | The quantity of space an object occupies |

Newton's Second Law | The acceleration of an object is directly proportional to the net force acting on the object, is in the same direction of the net force, and is inversely proportional to the mass of an object; acceleration=net force/mass |

terminal speed | The speed at which the acceleration of a falling object terminates because air resistance balances gravitational force; acceleration is zero & net force is zero; resistance=force due to gravity |

terminal velocity | terminal speed WITH direction |

Newton's Third Law | Every action has an opposite & equal reaction |

components | Mutually perpendicular vectors, usually horizontal & vertical, whose vector sum is a given vector |