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# Physics

### Definitions (OCR A2)

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

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

Amplitude | Maximum displacement from rest or equilibrium position (m) |

Angular frequency | Omega. It’s 2πf |

Boyle’s law | The volume of a fixed mass is inversely proportional to pressure exerted on it, provided temperature is constant. |

Displacement | Displacement of a body from rest or equilibrium position (m) |

Frequency | Number of oscillations per unit time (Hz) |

Geostationary orbit | Orbit of the Earth made by a satellite that has the same period as the rotation of earth and is in the equatorial plane. |

Gravitational field strength | is the force per unit mass at that point. |

Impulse | Product of force acting on a body and the time it acts. Also be considered as change in the momentum of a body. |

Inelastic collision | A collision where momentum is conserved but kinetic energy is not. |

Intensity | Power per unit cross-sectional area |

Internal energy | The sum of a random distribution of kinetic and potential energies of the particles of a system. |

Linear momentum | The product of mass and velocity, giving a vector quantity. |

Mole | 1 mol contains 6.02x1023 particles – which is the Avogadro constant. |

Net force | Equal to the rate of change of its momentum |

Newton’s law of gravitation | The gravitational force of attraction between two bodies is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centres. |

Perfectly elastic collision | A collision where kinetic energy and momentum are conserved. |

Period | The time taken for one complete pattern of oscillation (s) |

Phase difference (oscillations): | A measure of the relationship between the pattern of vibration at two points. |

Pressure | Force per unit area (Pa). 1 Pa = 1Nm-1 |

Radian | Unit of angle or phase difference (rad). One radian is the angle subtended at the centre of a circle by an arc of circumference that is equal in length to the radius of the circle. |

Simple Harmonic Motion | SHM occurs when the acceleration of a mass is directed towards a fixed point and is proportional to its displacement from that point a is proportional to x |

Specific heat capacity | The energy required to raise the temperature of 1 kg of a substance by 1 K. (J kg-1 K-1) |