**Description**

The programme looks at acceleration and the centripetal force which is experiences by objects moving in a circular path.

Module code and title: | S271, Discovering physics |
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Item code: | S271; 02 |

First transmission date: | 03-03-1982 |

Published: | 1982 |

Rights Statement: | |

Restrictions on use: | |

Duration: | 00:25:00 |

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Producer: | Tony Jolly |

Contributors: | Alan Durrant; Stuart Freake |

Publisher: | BBC Open University |

Keyword(s): | Aircraft; Astronauts; Centripetal force; Pendulum accelerometer; Pilots; Satellites; Space stations; Turntable |

Footage description: | Alan Durrant introduces the programme with a demonstration of a simple pendulum accelerator mounted on a trolley which is accelerated along a track. Shots of a London Tube train, of a drag racing car and of a Bucanneer jet at take-off Commentary explains that these are all examples of acceleration. Shots of a pendulum accelerometer rotating on a turntable. This is an example of acceleration at constant speed (centripetal acceleration.) An animated diagram shows a cannon firing projectiles at ever increasing velocities until they orbit the earth; again an example of centripetal acceleration. Shots of an artificial satellite in earth orbit. Stuart Freake, using a pendulum accelerometer mounted on a rotating turntable, demonstrates that speed of retation and the position of the pendulum on the turntable are both determinants of the magnitude of centripetal acceleration. Stuart Freake performs a quantitative experiment using a rotating puck floating on a cushion of C02. He works out the speed of the puck as well as the period of rotation and the circumference of the circle of rotation. Alan Durrant and Stuart Freake then explain how the figures obtained above can be used to work out a figure for the acceleration. Shots of a drawing board, of the rotating puck, and an animated diagram showing velocity vectors. Stuart Freake works out the acceleration for several velocities and arrives at the limit which is the instantaneous acceleration. Stuart Freake then briefly demonstrates how the direction of acceleration is determined. Alan Durrant explains a more theoretical approach which leads to a simple equation for working out the instantaneous acceleration. He uses a graphics board to help illustrate his points. Stuart Freake tests the formula obtained above against the results obtained from the puck experiment. Over shots of a model of a space station, Alan Durrant explains how centrepetal acceleration can be put to use to provide artificial gravity aboard, a space station. Shots of Alan inside a mock-up of the space station. He goes on to work out the required rate of rotation for creating a centripetal acceleration of one gravity. Over shots of the Red Arrows acrobatic flying team commentary points out the centripetal forces encountered by the pilots. It goes on to calculate the magnitude of the centripetal forces acting during certain manoeuvres Alan Durrant summarises the programme. |

Production number: | FOUS247B |

Videofinder number: | 1781 |

Available to public: | no |