Re: "Is There a Force of Gravity?"


"N:dlzc D:aol T:com (dlzc)" <N: dlzc1 D:cox T:net@xxxxxxxxxx> wrote in
message news:zaf7f.90866$lq6.64225@xxxxxxxxxxxxx
> Dear Harry:
>
> "Harry" <harald.vanlintel@xxxxxxx> wrote in message
> news:435d0b79$1@xxxxxxxxxxxxxxxxxxx
> >
> > "N:dlzc D:aol T:com (dlzc)" <N: dlzc1 D:cox T:net@xxxxxxxxxx>
> > wrote in
> > message news:HPZ6f.90801$lq6.43459@xxxxxxxxxxxxx
> >> Dear Daniel Weston:
> > SNIP
> >
> >> Contact forces provide the sensation of gravity. Note that
> >> when you throw a ball, and observe its "parabolic path",
> >> it is not the ball that is accelerating. *Your* feet are in
> >> contact with the Earth, you are accelerated.
> >
> > Hmm... then, if *you* live in, say, Switzerland and you are
> > *really* (remember, that was the issue) accelerated by
> > being in contact with the earth, then the same is true for
> > a guy living in the south of New-Zealand.
>
> Correct. If the Earth was condensed to a BH, each would follow
> an elliptical orbit, with maximum altitude just about where they
> (would have) started... Switzerland and New Zealand. They are
> each accelerated into a circular orbit, for which they have
> insufficient energy ot maintain, without the support of the
> Earth.
>
> > OK? But he accelerates in the opposite direction. Thus
> > according to you, New-Zealand and Switzerland are
> > *really* accelerating away from each other by 20 m/s^2...
> > I'd say that it's not Daniel who went over to the Dark Side!
>
> I see the mouth moving, but can make no sense of the "sound". If
> it is important, please try again.
>
> David A. Smith

As you commented on:
"gravity is not pulling me down in my chair, but rather the chair is
accelerating up towards me",
your discussion was about gravitation, not about rotation (I don't think you
included that in your example, right?). Also I did not include rotation in
the argument. Thus, taking a non rotating earth, read it again; you will
find no "orbits" but straight line accelerations and it will be clear -
hopefully.

Cheers,
Harald


.

Relevant Pages

  • Newtons Principia: Definitions: I - IV
    ... The motion of the whole is the sum of the motions of all the parts; ... Of this sort is gravity, by which bodies tend to the centre of the ... earth, but would go off from it in a right line, and that with an ... accelerates all falling bodies, whether heavy or light, great or ...
    (sci.physics)
  • Newtons Principia: Definitions: I - IV
    ... The motion of the whole is the sum of the motions of all the parts; ... Of this sort is gravity, by which bodies tend to the centre of the ... earth, but would go off from it in a right line, and that with an ... accelerates all falling bodies, whether heavy or light, great or ...
    (sci.physics.relativity)
  • Re: "Is There a Force of Gravity?"
    ... >> But he accelerates in the opposite direction. ... As the diameter of the earth can be found by subtracting the coordinates of ... > of gravity, ... > expanding, objects on the surface would resist ...
    (sci.physics.relativity)
  • Re: Rotating Earth and its effect on Gravity
    ... affected by the rotation of the earth. ... gravitational acceleration derived from Newton's law of Gravitation, ... It is clear that if the earths rotation were to increase in speed then ... outwards which causes the force of gravity to reach zero and then ...
    (sci.physics)
  • Re: Titanomachy
    ... :>> is slowing the earth's rotation. ... :>> The earth is not perfectly rigid. ... :>> stronger gravitational effect from the moon than the part facing ... :>> interaction with the moon's gravity will no longer produce tides, ...
    (sci.physics)