as earth rotates, top of tower is rotating at different speed to bottom of tower
On Tuesday, 3 March 2020, 17:03:16 GMT, H LV <[email protected]> wrote: On Tue, Mar 3, 2020 at 10:23 AM H LV <[email protected]> wrote: > At the time of Galileo it was argued the Earth could not be spinning because > this motion would result in an observable effect on the trajectory falling > bodies. For example if the Earth were turning eastward at hundreds of miles > per hour then a cannon ball dropped from a tower would not fall vertically > but would hit the ground west of the tower. In otherwords the ball would not > be able to keep up with the motion of the Earth. To counter this argument > Galileo formulated a thought involving a ship in his Dialogue Concerning the > Two Chief World Systems : > > <<Shut yourself up with some friend in the main cabin below decks on some > large ship, and have with you there some flies, butterflies, and other small > flying animals. Have a large bowl of water with some fish in it; hang up a > bottle that empties drop by drop into a wide vessel beneath it. With the ship > standing still, observe carefully how the little animals fly with equal speed > to all sides of the cabin. The fish swim indifferently in all directions; the > drops fall into the vessel beneath; and, in throwing something to your > friend, you need throw it no more strongly in one direction than another, the > distances being equal; jumping with your feet together, you pass equal spaces > in every direction. When you have observed all these things carefully (though > doubtless when the ship is standing still everything must happen in this > way), have the ship proceed with any speed you like, so long as the motion is > uniform and not fluctuating this way and that. You will discover not the > least change in all the effects named, nor could you tell from any of them > whether the ship was moving or standing still. In jumping, you will pass on > the floor the same spaces as before, nor will you make larger jumps toward > the stern than toward the prow even though the ship is moving quite rapidly, > despite the fact that during the time that you are in the air the floor under > you will be going in a direction opposite to your jump. In throwing something > to your companion, you will need no more force to get it to him whether he is > in the direction of the bow or the stern, with yourself situated opposite. > The droplets will fall as before into the vessel beneath without dropping > toward the stern, although while the drops are in the air the ship runs many > spans. The fish in their water will swim toward the front of their bowl with > no more effort than toward the back, and will go with equal ease to bait > placed anywhere around the edges of the bowl. Finally the butterflies and > flies will continue their flights indifferently toward every side, nor will > it ever happen that they are concentrated toward the stern, as if tired out > from keeping up with the course of the ship, from which they will have been > separated during long intervals by keeping themselves in the air. And if > smoke is made by burning some incense, it will be seen going up in the form > of a little cloud, remaining still and moving no more toward one side than > the other. The cause of all these correspondences of effects is the fact that > the ship's motion is common to all the things contained in it, and to the air > also. That is why I said you should be below decks; for if this took place > above in the open air, which would not follow the course of the ship, more or > less noticeable differences would be seen in some of the effects noted.>> > > This is a good argument that a spinning Earth won't result in falling bodies > being left behind but should it also be enshrined as a fundamentally true > principle of motion? > > Harry I mean it is one thing to argue that a revolving Earth and all bodies resting on the ground or in free fall share the same velocity as the ground. It is quite another to teach that all motion is relative. Harry
