Speed of the Earth

"Todd Smith" wrote in message
m...
What is the total velocity (say, of a point 5ft above the surface of
the earth) of the motion we experience every day when you take into
account all the translations, rotations and orbits of the earth
through the solar system and the solar system through the galaxy, and
the expansion of the universe (given an independent coordinate
system)?

-thanks
-Todd

Weeellll - lets see - ummmm
In relation to the sun - w = angular momentum, so w = circumference/theta
radians per time measure, but I forget - lets jst say take that in 1/365.25
of a year, the earth moves a little over 1 degree of arc around the sun. So
take the earth's distance from the sun (1AU = 8.5 light minutes , or look it
up somewhere), work out the circumference = 2 pi r, and then use your good
old v=u+at or s=whatever in realtion to work out displacement and time.
You'll work out its a fair clip.
The spiral vector to which the sun is moving is positively languid - say
about several million years round the core. Look up suns distance from the
core, and then plot another circle, also can look up orbital period to work
out radial momentum, etc. etc.
But on the really big scales-
The earth's velocity in relation to the really big scales approximates zero.
well, not truly zero, but a figure approaching zero with all its figures on
the really ragged end of the comma/decimal point.
A point in space - well work it out - it wouldn't stick around long within
your frame of reference.
If you are building a time machine, this is a real bind, as if it isn't
anchored in a spatial location, you've got your work cut out for you, which
explains why all good time machines e.g. le Capitaine Picard's vessel are
also fictional starships, just to keep pace.

Use your brain, that's what its there for !

All the best,
Martin.