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# Physics: Units 5-9

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

Momentum | quantity defined as the product of the mass and velocity of an object |

Impulse | product of force and time over which a force acts |

Impulse-Momentum Theorem | I=Fnet x delta t= delta p |

Law of Conservation of Momentum | the total momentum of all objects interacting with one another remains constant regardless of the nature of the forces between the objects |

Inelastic Collision | a collision in which two objects stick together completely after colliding |

Elastic Collision | a collision in which the total momentum and KE is conserved (objects bounce off one another with no permanent deformation) |

Rotational Motion | movement in a circle or spinning |

Radian | angle formed when an arc length is equal to the radius of a circle |

Revolution | one time around the radius of a circle |

Angular Displacement | change in an angle (delta theta) |

Tangential Speed | the linear speed of something moving in a circular path |

Angular Speed | rate at which an object moves through an angle |

Centripetal Force | net force acting toward the center of a circle keeping an object moving in a circular path |

Tangential Acceleration | how the tangential velocity of a point changes with time (same as linear acceleration but is specific to tangential direction) |

Angular Acceleration | rate of change in angular speed |

Rotational Kinematics | applying kinematics equations to rotational problems |

Centripetal Acceleration | acceleration towards the center of a circle |

Centrifugal Force | imaginary outward force felt by observers moving in a circular path |

Newton's Law of Universal Gravitation | F=(GxM1xM2)/r squared |

Universal Gravitation Constant | 6.67408x10 to the -11 power |

Kepler's Second Law of Planetary Motion | an imaginary line drawn from the sun to any planet sweeps out equal areas in equal time intervals |

Kepler's Third Law of Planetary Motion | The square of a plant's orbital period is proportional to the cube of the average distance between the planet and the sun |

Black Hole | a region of space having a gravitational field so intense that no matter can escape |

Kepler's 1st Law of Planetary Motion | Each planet travels in an elliptical orbit around the sun with the sun at one of its focal points |

Center of Gravity | the point at which the mass of a body can be considered to be concentrated when analyzing translational motion |

Torque | a quantity that measures the ability of a force to rotate an object about some axis |

Lever Arm | r(sin of theta) or d(sin of theta) |

Rotational Equilibrium | when the net force equals zero |

Moment of Inertia | tendency of an object to resist a change in rotational motion |

Angular Momentum | product of the moment of inertia and the angular velocity |

Conservation of Angular Momentum | lowering the moment of inertia will increase the rotational speed |

Translational Kinetic Energy | KE=1/2(m)(v squared) |

Rotational Kinetic Energy | KE=1/2(I)(w squared) |

Fluid | a non-solid state of matter in which the atoms or molecules are free to flow |

Mass Density | concentration of matter in an object |

Buoyant Force | upward force exerted by a fluid on an object that is sitting in or floating on a fluid |

Pressure | magnitude of the force on a surface per unit of area |

Ideal Fluid | a fluid with no internal friction |

Archimedes' Principle | an object completely or partially submerged in a fluid experiences an upward buoyant force equal in magnitude to the weight of the fluid displaced by the object |

Pascal's Principle | pressure applied to a fluid in a closed container is transmitted equally to every point in the fluid as well as the walls of the container |

Venturi Effect | the speed of a fluid increases when the cross sectional area decreases |

Flow Rate | product of area times volume for fluid in a pipe |

Bernoulli's Principle | the pressure of a fluid decreases as the velocity of a fluid increases |

Ideal Gas Law | (P1V1)/T1=(P2V2)/T2 |

Temperature | the measure of the average KE of the particles of the substance |

Internal Energy | the energy of a substance due to both the random motion of its particles and to the potential energy that results from the distances and alignments of the particles |

Thermal Equilibrium | the state in which two physical bodies in contact with each other have identical temperatures |

Heat | energy transferred between objects because of a difference in temperature |

Specific Heat Capacity | the quantity of heat required to raise a unit of mass of homogeneous material by 1K or 1C given constant pressure and volume |

Calorimetry | an experimental procedure used to measure the energy transferred from one substance to another as heat |

Phase Change | physical change in a substance from one state of matter to another at constant temperature and pressure |

Latent Heat | the energy per unit of mass that is transferred during a phase change |

Hooke's Law | the restoring force of a string depends on the stiffness of the spring and the displacement from the string's equilibrium point |

Simple Harmonic Motion | vibration about an equilibrium position in which a restoring force is proportional to the displacement from the equilibrium |

Medium | physical environment through which a disturbance can travel |

Mechanical Waves | a wave that requires a medium to travel through (sound waves) |

Pulse Wave | a wave that consists of a single traveling pulse |

Transverse Wave | a wave whose particles vibrate perpendicularly to the direction that the wave is traveling |

Compressional Wave | a wave whose particles vibrate parallel to the direction that the wave is traveling |

Compression | region of a longitudinal wave where the pressure and density are at a maximum |

Rarefraction | region of a longitudinal wave where the pressure and the density are at a minimum |

Constructive Interference | a combining of two or more waves that results in a wave that is a sum of the two colliding crests/ troughs |

Destructive Interference | a combining of two waves that results in the waves and troughs canceling each other out to create either a smaller wave or no wave at all |

Infrasonic Waves | sound waves with frequencies below 20 Hz |

Ultrasonic Waves | sound waves with frequencies above 20,000 Hz |

Pitch | a measure of how high or low the sound is perceived to be, depending on the frequency |

Doppler Effect | an observed change in frequency when there is relative motion between the source of waves and the observer |

Intensity | the rate at which energy flows through a unit perpendicular to the direction of wave motion |

Decibel | a dimensionless unit that describes the ratio of two intensities of sound |

Resonance | a phenomenon that occurs when the frequency of a force applied to an object matches the natural frequency; resulting in a large amplitude of vibration |

Fundamental Frequency | the lowest frequency of vibration in a standing wave |

Harmonic Series | a series of frequencies that includes the fundamental frequency and successive harmonics |

Timbre | the musical quality of a tone resulting in the combination of harmonics present at different intensities |

Beat | periodic variation in amplitude of a wave that is the superposition of two waves of slightly different frequencies |

Reverberation | prolongation of a sound |

Electromagnetic Wave | a wave consisting of oscillating electric and magnetic fields, which radiate outward from the source at the speed of light |

Luminous Flux | rate at which light is emitted from a source (measured in lumens) |

Illuminance | luminous flux divided by surface area |

Reflection | the change in direction of an electromagnetic wave at a surface that causes it to move away from the surface |

Virtual Image | an image where light rays appear to diverge even though they aren't actually focused there; cannot be projected onto a screen |

Concave Spherical Mirror | a mirror whose reflecting surface is a segment from the inside of a sphere |

Real Image | an image formed by intersecting of light rays; can be projected onto a screen |

Paraxial Rays | light rays that are near to the principal axis of a mirror and are used in ray diagrams |

Spherical Aberration | a blurred image resulting from a spherically shaped mirror |

Magnification | the process of enlarging something in appearance rather than physical size |

Convex Spherical Mirror | a mirror with a reflecting surface of an outward-curved segment of a sphere |

Linear Polarization | the alignment of electromagnetic waves in such a way that the vibrations of the electric fields in each of the waves are parallel to each other |

Refraction | the bending of a wave front as a wave passes between two substances in which the speed of the wave differs |

Index of Refraction | the ratio of the speed of light in a vacuum to the speed of light in a given transparent medium |

Snell's Law | n1sin(theta1)=n2sin(theta2) |

Lens | a transparent object that refracts light rays such that they converge or diverge to create an image |

Converging Lens | thick in the middle and thinner on the edges (convex) |

Diverging Lens | thin in the middle and thicker on the edges (concave) |

Total Internal Reflection | the complete reflection that takes place within a substance when the angle of incidence of light striking a surface boundary is greater than the critical angle |

Critical Angle | the angle of incidence at which refracted light makes an angle of 90 degrees with the normal |