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# A level Physics 4 Df

### Definitions

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

Absolute zero | The temperature at which a substance has minimum internal energy. | |

Amplitude | is the maximum displacement from the centre of an oscillation/ equilibrium position | |

Angular frequency | Rate at which central angle changes each second | |

cycle | A complete movement of an oscillating or cycle | |

Boyles Law | For a fixed mass of gas at constant temperature, the product of pressure and volume is constant | |

Centripetal acceleration | Acceleration of a body following a circular path: directed towards the centre of a circle. It is perpendicular to the velocity | |

Centripetal force | Resultant force that has to act towards the centre of a circle to make a body follow a circular path. It is perpendicular to the velocity. | |

Heavy damping | Heavy damping in which the system takes a long time to reach equilibrium. | |

Critical damping | Critical damping where the system reaches equilibrium in a short time compared with T with no overshoot where T is the natural period of vibration of the system. Time to damp about ¼ of period of oscillation | |

Phase difference | between two points in an oscillation is a measure of what fraction of a complete oscillation has been completed between the two points | |

Pressure Law for gases | For a fixed mass of gas at constant volume, the pressure is directly proportional to the temperature measured in kelvin | |

Radian | Central angle of a circle where arc length = radius | |

Resonance | The large amplitude oscillations that arise as a result of an oscillatory system being driven at a frequency equal to its natural frequency.Maximum energy transfer | |

Simple harmonic motion definition | If the acceleration restoring force of a body is directly proportional to its distance from a fixed point and is always directed towards that point in its motion it is said to be SHM | |

Specific Heat Capacity | is the heat required to produce unit rise in temperature in unit mass of the material | |

Specific Latent Heat | The specific latent heat of transformation from one phase to another is the energy needed per unit mass of the substance for the phase change to occur without any change of temperature occurring | |

Time period | Time for one complete rotation or oscillation | |

displacement | How far and in what direction the body is from its equilibrium position | |

Free oscillation | Simple harmonic motion with a constant amplitude and period and no external influences | |

Frequency | The number of oscillations completed per second | |

Gravitational Field lines | The direction in which a mass will move. Spherical masses produce radial fields. Near the earth we assume that the field is uniform. Gravitational fields are attractive only. | |

Gravitational field strength | Force per unit mass in a gravitational field | |

Hookes Law | Force is directly proportional to extension. F =kx up to the limit of prpportionality | |

Ideal gas equation | An ideal gas obeys the gas laws and pV =nRT exactly. No such gas exists. | |

In Phase | Two points which are in phase have a complete number of oscillations between them. | |

Internal Energy | is the sum of the random distribution kinetic and potential energies possessed by the atoms or molecules in a system | |

Isochronous | Time period is constant | |

Kepler’s third law | T2 proportional to r3 | |

Newton’s Law of Gravitation | Every particle in the universe attracts every other particle with a force directly proportional to the product of their masses and inversely proportional to the square of their distances apart. | |

One mole | One mole of a substance contain 6.02 x 1023 particles and that 6.02 x 1023mol-1 is the Avogadro constant NA. | |

Out of phase | Completely out of step with each other, π or 180. | |

Period | The periodic time is the time taken to make one complete oscillation/rotation | |

Pressure | Force per unit area | |

Natural Frequency | The frequency at which a free standing system oscillates after it has been displaced and then released |