Re: Issac newton &the downhill test adventure

Michael Press wrote:
In article <wuednWc8_tz4gdrZRVn-gg@xxxxxxxxxxx>,
"Phil Holman" <piholmanc@yourservice> wrote:

"Michael Press" <jack@xxxxxxx> wrote in message
news:jack-DD7DD4.12231219042006@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
In article
<timmcn-D6A3DC.08431519042006@xxxxxxxxxxxxxxxx>,
Tim McNamara <timmcn@xxxxxxxxxxxxx> wrote:

In article <kBm1g.3550$B42.2232@dukeread05>,
"Phil, Squid-in-Training" <phil_leeIHEARTBASHGUARDS@xxxxxxxxxxx>
wrote:

stankurz@xxxxxxxxx wrote:
I am 220 +/- my friend is 150 +/-. He has a relatively new mirage
grupo I have a mich-mach grupo but!!!?!: dura ace front and Phil
rear hubs. When we coast downhill I usually beat him often by
significant lengths. Is weight a factor [pace Issac]? I assume
that
it is the quality of the hubs that makes the difference. Thmx

Uh... duh... Galileo did this little test a little while ago. He
dropped weights from the Leaning Tower of Pepperoni Pizza and
determined, since the heavier weight hit the ground first, that
heavy
things fall faster.

Think about it... drop a feather and a bowling ball at the same
time.
Which one hits the ground first?

How about in a vacuum?

Tim, you misread Phil's article.

and so did I............. the Equivalence Principle says that
gravitational mass is equal to inertial mass and that all objects
fall at the same rate in a vacuum. According to GR, gravity is not a
force but a distortion of space. The feeling of weighlessness during
freefall is unique for an accelerating body i.e. any other
acceleration is accompanied by a feeling of being pushed.

and from the heavier body's point of view it takes longer
to reach the ground.

The USA global positioning satellite system is based upon
accurate clocks aboard orbiting satellites broadcasting
their time and other information. When the system was
designed they naturally built the Lorentz transformations
into the satellite clocks and computers. One bright light
said that they also needed to add in the variance of clock
rate from the gravitational field differences between
terra firma and the satellite altitude; but he was
ignored. When the system was being tested they discovered
systematic errors; eventually determined that the errors
were from gravitational effects on the clocks that were
tuned at sea level, but running at a few hundred
kilometers altitude.

From Wikipedia:

GPS and relativity

The clocks on the satellites are also affected by both special and general
relativity, which causes them to run at a slightly faster rate than do
clocks on the Earth's surface. This amounts to a discrepancy of around 38
microseconds per day, which is corrected by electronics on each satellite.
This offset is a practical demonstration of the theory of relativity in a
real-world system; it is exactly that predicted by the theory, within the
limits of accuracy of measurement.
Neil Ashby presented a good account of how these relativistic corrections
are applied, why, and their orders of magnitude, in Physics Today (May 2002)
[7]. Whether relativity must be considered as a mere correction to a
Newtonian GPS theory, or, rather, as the necessary foundation of a cleaner
(and more fundamental) GPS theory, is currently under debate. Bartolomé Coll
has recently developed the basic notions necessary for a fully relativistic
theory of Positioning Systems [8].

--
Phil, Squid-in-Training


.

Relevant Pages

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