The Foucault Pendulum is a fascinating thing.
I suppose the best place to observe one is at
the poles where the complete rotation can be
seen. Indeed, in summer time at the north pole
it would be even more weird since it would be
turning in time with the sun. I'm sure the
ancient egyptians who worshipped the sun could
have made something out of that.
I have always felt a bit sorry for people
living on the equator since a Foucault Pendulum
wont work there. Musing on their misfortune I
came up with a pendulum which would. Namely,
a compound pendulum of infinite effective
length; what one might describe as an Equatorial
Foucault Pendulum (EFP)
As Vorts, doubtless, are well aware the effective
length of a compound pendulum is given by the
formula,
L = I/(Md)
Where L is effective length
I is the moment of inertia about
the pivot point
M is the mass of the pendulum
d is the distance between the body's
centre of mass and the pivot point.
Where d equals nought, L equals infinity.
So if we have two very heavy balls at each end
of a long lever arm which is pivoted exactly
at the centre of mass then d = 0 and, effectively,
we have a compound pendulum of infinite length.
Now if we set up the EFP horizontally at the
equator with the lever arm aligned in a east
west direction, as the earth rotates the EFP
should describe a vertical circular a rate
of 15 degrees per hour.
If the beam was released at sunrise the eastern
ball would rise with the sun and follow it round
the sky eventually setting as the sun set. One
could paint the eastern ball gold and the western
ball black. I'm sure the African witch doctors
would love it and it would give a whole new meaning
to the terms Golden Balls and blackball.
I suppose if you made one big enough you could
actually extract energy from it - at the expense
of slowing down the earth a bit. Still, it would
be a favour to all those born on the 29th of
February to get rid of the leap year. One might
even slow it down to the Babylonian 360 days,
which would be rather neat.
I can't see any snags to an EFP working in principle.
Perhaps Horace can. ;-)
Cheers
Frank Grimer
