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"But you can't measure the force that way."Says who?I could, were I so minded measure the distance between my hindquarters and the ground as a function of time, calculate the acceleration (it will be close to 8.9 m/s/s) and since I know that M is 70 Kg, I can calculate F which will be close to 700N).
the net force is almost entirely the force of gravity and I will fall towards the centre of mass of the earth - the force is calculated with F=GMearthMmeR^-2 , to get the acceleration divide the force by my mass a=GMearthR^-2; at the earth's surface this is damn near constant at 9.8ms^-2. This will agree with timing of Geezer tumbling onto the floor after the chair is pulled away
Quote from: Bored chemist on 26/08/2011 20:16:52"But you can't measure the force that way."Says who?I could, were I so minded measure the distance between my hindquarters and the ground as a function of time, calculate the acceleration (it will be close to 8.9 m/s/s) and since I know that M is 70 Kg, I can calculate F which will be close to 700N).Says me.You are in "free fall" accelerating towards the Earth. Your measurements always produce the same result, even if you vary your mass. What do you suppose you are measuring?
Quote from: Geezer on 26/08/2011 21:10:27Quote from: Bored chemist on 26/08/2011 20:16:52"But you can't measure the force that way."Says who?I could, were I so minded measure the distance between my hindquarters and the ground as a function of time, calculate the acceleration (it will be close to 8.9 m/s/s) and since I know that M is 70 Kg, I can calculate F which will be close to 700N).Says me.You are in "free fall" accelerating towards the Earth. Your measurements always produce the same result, even if you vary your mass. What do you suppose you are measuring?Nonsense.I can see the ground coming towards me if I fall towards it.As I already said "I could, were I so minded measure the distance between my hindquarters and the ground "so why do you ask "What do you suppose you are measuring?"?
"With respect to what am I currently accelerating that explains the dent in the springs in the chair I'm sitting on?"
I'm not trying to come up with an alternative to GR. I'm trying too get you to explain yourself, but you seem unable or unwilling to do so.So, for the third time of asking"With respect to what am I currently accelerating that explains the dent in the springs in the chair I'm sitting on?"And, while you are at it, why do you think you can add together quantities with different units? And do you consider friction to be an acceleration?
"With respect to what am I currently accelerating that explains the dent in the springs in the chair I'm sitting on?"And, while you are at it, why do you think you can add together quantities with different units? And do you consider friction to be an acceleration?
Now we have that sorted out, perhaps we can get back to the OP's point.They contend that "person inside the air craft reduces its own gravity force due to speed."
And I disagree, because I don't seem to weigh less when I'm in a plane.In a plane I am travelling fast so, WRT me, the earth is travelling fast. But it still seems to hold the same attraction for me.As I said, we are not talking about the effect of altitude on gravity here, nor the effect of the plane rising or falling.Just to keep it simple we are on a plane in level flight (i.e. at a constant height WRT the Earth's C of G).Given that starting point, it seems to me that the OP is mistaken.
I think what the poster might be describing (though the question was worded in a confusing manner) is that you appear weightless when in orbit.
Quote from: JP on 06/09/2011 17:57:13I think what the poster might be describing (though the question was worded in a confusing manner) is that you appear weightless when in orbit. But you don't need to be in orbit. To become weightless, all you need to do is jump so that your feet are no longer in contact with anything.