From: "Gary Britt" 

I thought the acceleration of gravity was 9 ft per sec per sec?  Am I just
remembering this wrong?

Gary

"Monte Davis"  wrote in message
news:s1fl12ldss74oq3d278261u4jhc6vcqn07{at}4ax.com...
> "Geo"  wrote:
>
> >I thought you could go into orbit at
> >150 miles?
>
> Yes, you can -- and in that orbit, you weigh >95% of ground weight,
> meaning you're falling at ~31 feet/sec/sec. You don't hit because
> you're also moving sideways at 17,500 mph... so as you fall, the
> earth's surface below is curving "down and away" at a rate that
> exactly compensates. You're falling *around* the earth.
>
> It's simple accuracy, not pedantry, to describe orbit as "free fall"
> rather than "weightlessness" or "zero-g." The
floating-around part is
> because the astronaut, vehicle and everything in it are all falling at
> the same rate. (the old broken-elevator-cable trick, it just doesn't
> stop)
>
> Think about it: you're 3960 miles from the earth's center right now.
> Even with an inverse-square force, 150 miles up is a pretty small
> increment; you'd need to be 3960 miles up for 2x the distance, 1/4 the
> gravity.
>
> So a low orbit is mostly about velocity and only a little about weaker
> gravity. As you go up, that balance shifts. A satellite in GEO needs
> about 7000 mph, and the moon lazes along its orbit at maybe 2000 mph.
> They are ALL FALLING, ALL THE TIME.
>
> (There, don't you worry less about terrorism now?)
>
>
>

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