"Cecil Moore" bravely wrote to "All" (22 Dec 05 14:47:46)
--- on the heady topic of " Antenna reception theory"

CM From: Cecil Moore
CM Xref: core-easynews rec.radio.amateur.antenna:221698

CM Asimov wrote:
If I can manage to roll the boulder up at the top or at the bottom of
the cliff, I will find it weighs about the same. The boulder only
picks up energy as it is accelerating towards the foot of the cliff.

CM Energy cannot be created or destroyed. The kinetic energy gained
CM as it accelerates is exactly balanced by the loss in potential
CM energy that it had at the top of the cliff.

CM Consider a pendulum. When it stops at the limit of its swing,
CM it possesses potential energy. When it is moving at its fastest
CM at the bottom of its swing, it possesses kinetic energy. When
CM it finishes the swing to the other limit, it possesses potential
CM energy. Neglecting losses, potential energy at the top of the
CM swing is converted into an equal magnitude of kinetic energy at
CM the bottom of the swing and back to potential energy at the top
CM of the swing.

Consider the Earth-Moon system, they interact via the oceans on Earth.
The water level bulges can be considered as the pendulum in your
example. The result of the tide is that gravitational energy is being
transfered to the Moon and it is gradually accelerating away from the
Earth. So in your example the pendulum doesn't have any energy except
that which it borrows and returns to the Earth's pull of gravity. If
we were to follow your logic the Moon should fall to the Earth
instead. Assuming frictionless bearings and zero drag your pendulum
should go on forever because it has no energy of its own.

A*s*i*m*o*v