Foucault Pendulum, Introduction Latest change 2017-11-27
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A Foucault Pendulum consists of a thin wire on which a weight is suspended. The weight
can swing freely in any direction, and suppose it is swinging in East-West
direction at a certain moment, a few hours later it will swing in
another direction because the earth is rotating below it.(*)
The behaviour of a Foucault Pendulum gives a rather direct evidence
the earth is rotating.
The challenges are:
- Mounting and driving the pendulum such that there is no
preference for a certain direction.
- Suppressing the elliptical orbit any free hanging pendulum
tends to develop.
- The technique for tracking and logging the behaviour of the
- The web technique to stream real-time images and
to present the logged data.
My plan is to:
- Build a pendulum in my home and evaluate the requirements
for driving and tracking (winter - summer 2016/2017)
- Mount a pendulum in the chapel at Vrijland. Here we
implement the web-technique.
If all is well you can watch my pendulum here in real time: http://184.108.40.206:4242
login / pw Foucault / Leon (for unclear reasons this does not work)
Here is a short movie of the pendulum at my home.
(*) Only at the North- or Southpole the plane of swinging will rotate
in 1 day(**). At lower lattitudes it goes slower, with
1/sin(lattitude) and on the equator it does not work at all because
sin(lattitude) will be zero and the swinging plane will take infinite
(**) This is the siderial day, that is the time in which the earth
makes one revolution w.r.t. the far, fixed stars. That time is