I can imagine a well hole from pole to pole. The gravitational force on a ball at the center of the earth is null. Assuming the well hole is structurally impervious, and evacuated, the ball dropped at the north pole would fall, accelerating ever more slowly, until it reached zero acceleration at the Earth's center, and as it continued to fall toward the south pole it would slow, until it reached zero speed at the earth's surface at the south pole, whereupon it would fall back into the hole, and continue oscillating. It the hole were not evacuated, friction would cause the ball to stop at the earth's center. If the well were not impervious, it would collapse, and the ball would rest at the bottom of the well. A "deeper" hole could be imagined, if there were a black hole at the center of the earth. The ball would check in, and wouldn't check out. Until the black hole evaporated. -----Original Message----- From: Rodney Austin [mailto:rodcomet@gmail.com] Sent: Saturday, December 20, 2008 19:14 To: seesat-l@satobs.org Subject: Somewhat OT Interesting Question in a survey Hi All, I have just been answering a survey designed to study the understanding of astronomical concepts among school children. The author of the survey has asked several local 'experts' including myself (Ha!) to also do the survey to study the differences etc. One question was sufficiently curly to cause quite discussion at the New Plymouth Astronomical Society last night. Logic and intuition seem to break down when studying the ramifications of the question. At first glance it is very straight forward. Question. Imagine that you dropped a ball into a very deep well hole (as deep as you can imagine). There is no water in the well. What would happen to the ball and why? I would be most interested to hear your opinions on this one. Merry Christmas and Happy New Year to you all. Cheers Rod Austin ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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