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Pendulums There are a number of different forms of pendulum. The main characteristic being that when the mass is displaced from it's position of rest it will oscillate at a fixed frequency. Simple Pendulum - As used in the simplest mechanical clock designs.
  - where
- τ = period [s]
- l = length [m]
- g = gravitational acceleration [ms-2]
| | Conical Pendulum - Note that it would be necessary to throw the bob into a circular motion to start it and then once settled the equation may be applied.
  - where
- τ = period [s]
- l = length [m]
- α = cone half-angle [rad]
- g = gravitational acceleration [ms-2]
| | Torsional Pendulum - Another simple design used in some types of clock.
  - where
- τ = period [s]
- l = length [m]
- I0 = moment of inertia of bob [kgm2]
- kt = torsional rigidity [Nm2]
| | Historical Notes - 1581 Galileo uses his pulse to time the swinging of the lamps in the cathedral at Pisa. He concludes that the time for a lamp to swing does not depend on the angle through which it swings. This observation eventually leads to the development of pendulum clocks.
See also: Schuler Pendulum, Simple Harmonic Motion.
  
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