If a stone is dropped from a balloon on a still day, does the stone fall directly below the balloon, or to the west or east of it?

Einstein would have consider the balloon, rock and Earth to a 'closed' system. 

In other words, we disregard all outside influences, which includes the rotation of the Earth and is revolution around the Sun.

In this system, everything moves (or stays put) relative to the centre of the Earth.

Therefore the balloon would not more (relative to the Earth) and the stone would drop directly below the balloon.

Viewed from a point away from the Earth however, one would notice the rotation of the Earth, the comparable rotation of the balloon and corresponding rotation of the dropping stone, which would be on a line directly from the balloon towards the centre of the Earth.

Posted by brianjn on 2005-07-08 00:52:29