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От : vallor 2:5075/128 01 июл 23 13:59:33
К : Stefan Ram 01 июл 23 17:06:12
Тема : Re: Question regarding an elevator
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@REPLYADDR vallor <vallor@vallor.earth>
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On 1 Jul 2023 11:44:31 GMT, Stefan Ram wrote:
> vallor <vallor@cultnix.org> writes:
>>I was referring to the observation that Einstein made that one couldn`t
>>tell the difference from within an elevator in either situation. I was
>>pointing out that with sensitive enough instruments,
>>you can tell the difference.
>
> The gravitational potential at the bottom of the elevator is
>
> V( x )= -GM/x, where
>
> x is the distance from the center of the Earth to the bottom
> of the elevator,
> G is the gravitational constant, and M the mass of the Earth.
>
> At the top, it`s
>
> V( x + h )= -GM/( x + h ), where
>
> h is the height of the elevator.
>
> So the difference is
>
> -GM/( x + h )-( -GM/x )= GMh/( x^2 + hx )~ GMh/x^2.
>
> This difference can be made as small as wanted by reducing the height
> of the elevator. We also should reduce the size of the floor as
> otherwise the direction of the force differs between different points
> of the floor. So, it seems to me that for such gedanken-experiments
> one uses elevators of infinitesimal size!
Thank you so much for doing the math. It`s been a while.
Also, it seems to me that for an elevator accelerating at 1G
in free space, the "top" accelerometer will actually
register _heavier_ than the "bottom" accelerometer, due to
gravity from the mass of the elevator.
--
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