Herbert Graf wrote:
> Consider a rocket with a force meter on the nose, and one on the tail,
> and the rocket is on the earth pointed straight up. On the pad the two
> meters would differ in reading, since the one on the tail is closer to
> the earth then the one on the nose.

Correct in theory, but now figure out the difference in practise, even for a
large rocket.  The radius of the earth is about 6.38Mm.  Let's say the large
rocket is 100m tall.  That yields a distance ratio of 1.0000157 between top
and bottom.  Gravity is proportional to 1/R**2, so the gravity ratio is
1.0000314, or about 31ppm.  Measuring accelleration to that accurracy is NOT
easy.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist