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# Topic 2 - Physics

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

Displacement | vector quantity that refers to the object's overall change in position |

Velocity | a physical vector quantity; both magnitude and direction are needed to define it; , being a coherent derived unit whose quantity is measured in the SI (metric system) as meters per second (m/s) or as the SI base unit of (m⋅s−1) |

Speed | a scalar quantity; the rate at which an object covers distance |

Distance | scalar quantity that refers to how much ground an object has covered during its motion |

Acceleration | vector quantity that is defined as the rate at which an object changes its velocity |

Instantaneous velocity | velocity of an object in motion at a specific point in time |

equations of uniformly accelerated motion | set of equations that describe an object's motion |

acceleration due to gravity | acceleration which is gained by an object because of gravitational force; a vector quantity - means it has both a magnitude and a direction; has a standard value defined as 9.8 m/s2 |

terminal velocity | the constant speed that a freely falling object eventually reaches when the resistance of the medium through which it is falling prevents further acceleration |

displacement time graphs | reveals useful information about the velocity of the object (i.e. the velocity of an object at a given time); graph of motion |

velocity time graphs | reveals useful information about the acceleration of the object; if the acceleration is zero, then the slope is zero (i.e., a horizontal line); if the acceleration is positive, then the slope is positive (i.e., an upward sloping line) |

acceleration time graphs | the change in velocity in a given time interval is equal to the area under the graph during that same time interval |

relative velocity | the vector difference between the velocities of two bodies; the velocity of a body with respect to another regarded as being at rest |

projectile motion | any object that once projected or dropped continues in motion by its own inertia and is influenced only by the downward force of gravity; also an object which is thrown upward at an angle to the horizontal |

inertia | the resistance of any physical object to any change in its state of motion (includes changes to the object's speed, direction, or state of rest); the tendency of objects to keep moving in a straight line at a constant velocity |

weight | force exerted on a body of gravity |

force | something that causes a change in the motion of an object |

Newton | the SI unit of force; equal to the force that would give a mass of one kilogram an acceleration of one meter per second per second |

Newton's first law of motion | an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force |

Newton's second law of motion | the acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object |

Newton's third law of motion | for every action, there is an equal and opposite reaction |

Free-body Diagram | diagrams used to show the relative magnitude and direction of all forces acting upon an object in a given situation |

Friction | refers to any force that resists relative tangential motion (slipping and/or sliding), or intended motion; its direction is opposite the relative velocity (or intended velocity) |

Static Friction | friction that exists between a stationary object and the surface on which it's resting |

Dynamic Friction | the force that must be overcome to maintain steady motion of one body relative to another because they remain in contact |

Normal Reaction/Force | support force exerted upon an object that is in contact with another stable object |

Tension | the force which is transmitted through a string, rope, wire, or cable when it is pulled tight by forces acting from each end; tensional force is directed along the wire and pulls equally on the objects on either end of the wire |

upthrust | the upward force that a liquid or gas exerts on a body floating in it |

lift | component of a force that is perpendicular to the oncoming flow direction; contrasts with the drag force, which is the component of the surface force parallel to the flow direction |

transitional equilibrium | when the sum of all the external forces acting on the object equals zero |

rotational equilibrium | the state of a system for which the total angular acceleration is zero |

energy forms and transfers (first 5) | 1. kinetic - motion 2. potential (gravitational) - position 3. electric/magnetic - charge 4. chemical - atoms 5. nuclear - △E=mc2 |

energy forms and transfers (second 5) | 6. elastic (potential) - deformation 7. thermal (heat) - △ in temperature 8. mass - conversion to binding energy 9. vibration (sound) - mechanical waves 10. light - photons |

work | then a force that is applied to an object moves that object |

joule | energy used to accelerate a body with a mass of one kilogram using one newton of force over a distance of one meter; also equivalent to one watt-second |

work done by a non-constant force | object moving into space experiences a varying force that has a magnitude inversely proportional to the square of the distance |

energy | ability to do work; exists in many forms |

kinetic energy | energy an object has because of motion |

gravitational potential energy | energy an object has because of position |

principle of conservation of energy | when energy changes from one form to another, we find that nothing is lost |

elastic collisions | collision in which there is no loss of kinetic energy in the collision |

inelastic collisions | collision in which part of the kinetic energy is changed to some other form of energy in the collision |

explosive collions | each object involved encounters the same impulse to cause the same momentum change; the impulse and momentum change on each object is equal in magnitude and opposite in direction |

power | rate of doing work; measured in Watts (W) |

efficiency | percentage of energy transfer |

linear momentum | vector quantity defined as the product of an object's mass, m, and its velocity, v |

impulse | vector quantity defined as the product of the force acting on a body and the time interval during which the force is exerted |

law of conservation of linear momentum | has constant magnitude and direction if the system is subjected to no external force |

force-time graphs | shows the force of an object at a given time on a graph |