[Physics] About the equivalence principle

[carmam at tiscali.co.uk]

Olivier, I used a miniature black hole simply because it is a massive object , yet is a similar size (approximately 10mm diameter) as the lead or wood which Einstein used.The reason that the lump of lead and piece of wood in Einstein's original Gedankenexperimente appear to fall at the same rate on Earth is that a mass of 1Kg and a mass of 100KG, when compared to a mass of 5.972e24 are virtually identical. The mass of the Earth is so much greater than either of them, that they appear to fall at the same rate. The acceleration the Earth imparts to an object of negligible mass at 20 metres height is 9.81947 M/s^2 .
To run through the calculations :-Acceleration of falling body of negligible mass on Earth :-
a = G * M / d  =  6.674e-11 * 5.972e24 / 6371020^2   =   9.81947 M/s^2 
The acceleration which an object of mass = 100Kg imparts to another mass at 20 metres is :-
a = 6.674e-11 * 100 / 20^2  =  0.000000000016685 M/s^2
The acceleration of an object of 1Kg mass is :-  
a = 6.674e-11 * 1 / 20^2  =  0.00000000000016685 M/s^2
An object of 100Kg mass falls at      9.81947000000016685 M/s^2 , while an object of 1Kg mass falls at  9.8194700000000016685 M/s^2 . 
That difference is minute, and just not noticed when watching, or even timing the fall of the different test masses. Now compare that to the acceleration caused by the combined gravities of the Earth and a miniature black hole, and you can see at once that a more massive object falls faster than a less massive one, as does a mass one half that of the MBH, or a mass of a tenth, or a hundredth etc. This means that a piece of wood falls slower than a lump of lead. Reductio ad absurdum.
Hope this helps,Tom.


----Original Message----

From: o.serret at free.fr

Date: 07/11/2016 23:22

To: <physics at tuks.nl>

Subj: Re: [Physics] About the equivalence principle







Tom,
 
To get a better understanding, why do you use a “black hole” ? and why not 
a usual body ?
 
Thank you
Olivier
 
 
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