soniccity

I think I'm getting it. Thanks.

I guess my question is that it takes the same time to fly SF to NY as it does NY to SF, save the prevailing headwinds. It would seem the rotation of the earth would make the west to east trip shorter duration but it doesn't. Spacecraft circumnavigate the earth based partly on earth rotation, yet aircraft don't. Obviously there is some fundemental principal I don't understand. That was point about 24000 MPH or roughly the speed of earth rotation. In my layman's conceptualization, the plane traveling SF to NY at 400 MPH is at the same time, traveling backwards, relative to space, along with the earth. Maybe I'm over thinking it. I have flown east to west at dusk, and the sunset takes longer than if on land, yet the time for distance travelled remains the same. Thanks for indulging my curious yet woefully ignorant inquiries. Getting back to the gravity question, isn't the pendulum effectively a perpetual motion engine?

Thank you for an informative reply. A pendulum makes some sense though I wonder about terminal velocity. Another question That has crossed my mind is one of air travel. I have asked many pilots about this and have never received a satisfactory answer. If I fly San Francisco to to new York, it takes roughly 4 hours to go 3000 miles west to east. Conversely, the return flight takes the same amount of time, give or take the jet stream. So the rotation of the earth doesn't factor in the travel time. Does that mean that as a plane travels west to east, its still travelling 24000 MPH the other way?

If I could drill a hole through the diameter of the earth to the other side and dropped a ball into that hole, what would happen when the ball reached the dead center? Not a trick question, I have no idea.