> I've been following this thread for a bit but haven't 
> really taken the
> time to think about the situation until now, and here's 
> what I came up with:
...

> When you're in open space with nothing around, net force 
> on both is zero.

> When a rocket engine pushes the accelerometer in open 
> space at 1g ...

> When the accelerometer is in freefall towards a planet 
> pulling at 1g ...

> When the accelerometer is sitting on a table in a g-field 
> of 1g ...


Yes. All that was essentially correct (IMHO of course :-) ).

There is one twist which may interest people.

> When the accelerometer is sitting on a table in a g-field 
> of 1g, the 1g
> gravitational force is applied to both the casing and the 
> ball, but the
> table's normal force of 1g is applied only to the casing 
> and not the
> ball. The accelerometer measures the difference of 1g.

Now stand in a sealed room with your ultra high resolution 
ultra high accuracy g meter.
Place the g meter on the floor.
Note that it reads 1.000000000000000000 g
Now raise the g meter to the ceiling and measure again.
Note that it still reads 1.000000000000000000 g.

1.    Given 2 options, are you able to conclude whether you 
are in a rocket accelerating at 1g or stationary near a 
planetary surface

2.    Does the answer seem to conflict with what Einstein 
says about the equivalence of gravitational fields.

3.    If the second reading above had been about 1 part in 
10^12 smaller than the first reading would it have changed 
your answer to question 1?



        Russell McMahon 

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