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# Physics

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 | The mass times the change in velocity or an object(momentum) equals the force times the amount of time (impulse). |

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 |

perfectly elastic collision | A collision in which the total momentum and kinetic energy are conserved |

perfectly inelastic collision | A collision in which two objects stick together completely after colliding |

energy in collisions | Inelastic collisions lose kinetic energy that is used to deform the objects. Elastic collisions conserve kinetic energy. |

rotational motion | movement in a circle or spinning |

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

angular displacement | change in angle |

angular speed | rate at which an object moves through an angle |

angular acceleration | rate of change in angular speed |

tangential acceleration | rate of change in linear velocity |

centripetal acceleration | acceleration toward the center of a circle |

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

gravitational force | force that is affected by the masses of objects and distances between them |

escape speed | the lowest velocity that a body must have in order to escape the gravitational attraction of a particular planet or other object |

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

lever arm | The radius times the sine of the angle |

center of gravity | point at which the mass of a body can be considered to be concentrated |

moment of inertia | tendency of an object to resist a change in rotational motion |

rotational equilibrium | The state of an object when there is no net force or net torque |

Newton's second law for rotational motion | The torque of an object will equal it's moment of inertia times it's angular acceleration |

angular momentum | moment of inertia times angular speed |

conservation of angular momentum | angular momentum is conserved as long as there are no external torques |

rotational kinetic energy | one-half the moment of inertia times angular speed squared |

efficiency | Ratio comparing the amount of useful work to total work |

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

mass density | concentration of matter in an object |

buoyant force | upward force exerted by a fluid on an object immersed in or floating on the fluid |

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

negative buoyancy | Buoyant force is less than downward force causing the object to sink |

positive buoyancy | Buoyant force is greater than downward force so the object floats |

apparent weight | gravitational force minus buoyant force, objects in fluids appear to weigh less |

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

Pascal's principle | pressure applied to a fluid in a closed container is transmitted equally to every point of the fluid and to the container |

absolute pressure | The gauge pressure plus the atmospheric pressure |

temperature | measure of the average kinetic energy of the particles in a substance |

viscosity | the resistance to flow of a fluid |

laminar flow | steady and smooth flow |

turbulent flow | rocky flow in different directions |

Venturi effect | The speed of a fluid increases while cross-section area descreases |

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

Bernoulli's equation | The pressure plus one-half the density times velocity squared plus the density times gravitational acceleration times the elevation has to remain constant |

ideal gas law | (P1V1)/T1= (P2V2)/T2 |

internal energy | the energy of a substance due to both the random motion of it's particles and to the potential energy that results from the distances and alignments |

thermal equilibrium | the state in which two bodies in physical contact with one another have identical temperatures |

thermal expansion | in general, increasing the temperature of a substance increases it's volume |

thermometer calibrations | based off of coefficients of volume expansion and calibrated using freezing and boiling points |

Celsius to Kelvin conversion | Tk= Tc+273 |

Celsius to Fahrenheit conversion | Tf= 1.8Tc+32 |

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

specific heat capacity | the quantity of heat required to raise a unit mass of homogenous material |

calorimetry | An experimental procedure used to measure the energy from one to another as heat. Hot objects are placed into a calorimeter and changes in temperature are recorded. |

latent heat | the energy per unit mass that is transferred during a phase change of a substance |

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

latent heat of fusion | amount of energy needed to melt one kilogram |

latent heat of vaporization | amount of energy needed to boil one kilogram |

thermal conduction | transfer of heat through direct contact |

clothing and climate | in cold climates, clothes are made out of thermal insulators that trap air in so your body heat stays in. In hot climates, clothes are worn that cast off heat easily. |

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

simple harmonic motion | vibration about an equilibrium position in which a restoring force is proportional to the displacement from equilibrium |

spring constant | stiffness of a spring |

elastic potential energy | energy stored in elastic materials when there is a displacement from equilibrium |

pendulum | a weight hung from a fixed point so that it can swing freely backward and forward |

amplitude | the maximum displacement from equilibrium |

period | the times it takes a complete cycle to occur |

frequency | the number of cycles or vibrations per unit of time |

medium | physical environment through which a disturbance can travel |

mechanical wave | a wave that requires a medium through which to travel |

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

periodic wave | wave formed by the periodic motion of a wave source |

crest | highest point above equilibrium position |

through | lowest point below equilibrium position |

transverse wave | a wave whose particles vibrate periodically |

longitudinal wave | a wave whose particles vibrate parallel to the direction the wave is traveling |

compressional wave | a wave whose particles vibrate parallel to the direction the wave is traveling |

wave speed | speed at which a mechanical wave travels depends on medium |

constructive interference | a superposition of two waves in which individual displacements on the same side of the equilibrium position are added together to form the resultant wave |

destructive interference | a superposition of two or more waves in which individual displacements on opposite sides of the equilibrium position are added together to form the resultant wave |

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

standing wave | a wave pattern that results when two waves of the same frequency, wavelength, and amplitude travel in opposite directions and interfere. |

compression | region of a longitudinal wave in which the density and pressure are at a maximum |

rarefaction | region of a longitudinal wave that in which the density and pressure are at a minimum |

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

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

intensity | the rate at which energy flows through a unit area perpendicular to the direction of the waves |

loudness | human perception of sound intensity |

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

decibel scale | based off of the threshold of human hearing; every increase in 10dB is equal to ten times the intensity of sounds |

natural frequency | the frequency at which an object will vibrate when set in motion |

resonance | a phenomenon that occurs when the frequency of a force applied to a system matches the natural frequency of vibration of the system, resulting in a large amplitude of vibration |

human hearing | humans can hear between 20 and 20,000 Hz |

overtones | integral multiples of the fundamental frequency |