pendulums under acceleration

[Brian D. McCary]

>From: Juan Cires Martinez:   .....
>If I remember correctly, the frequency of oscillation of a pendullum is
>proportional to the square root of the vertical acceleration (gravity's 
>acceleration when at rest).

Partially true.  Under the cited case of a pendulum on a vertically 
accelerating rocket, the restoring force on the pendulum would be the
combination of gravity and the thrust of the engines.  So you would
get a change in pendulum frequency, but you would be unable to tell if
it was from the rocket slowing down, or from altitude.  Furthermore,
changes in the gravitational constant over a few tens of km altitude
would probably be insignificant with respect to changes in thrust 
during the same cycle of the launch.

Brian McCary