Supplement to the first edition of ... elements of physics, or natural philosophy / [Neil Arnott].

  • Arnott, Neil, 1788-1874
Date:
1828
Catalogue details

Licence: Public Domain Mark

Credit: Supplement to the first edition of ... elements of physics, or natural philosophy / [Neil Arnott]. Source: Wellcome Collection.

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    At page 66, after line Ath (^' p. 63). It thus appears that the very fact of a spinning-top inclining, causes the point to shift its place, and so that it cannot rest until it come again directly under the centre of the top. It is remarkable that even in philosophical treatises of authority the standing of a top is still vaguely attributed to centrifugal force. Hence some persons believe, that a top spinning in a weighing scale, would be found -lighter 'than when at rest ; and many most erroneously hold that the centrifugal force of the whirling, which of course acts directly away from the axis, and quite equally in all direc¬ tions, when the top inclines, becomes greater upwards tlian downwards, so as to counteract the gravity of the to]). The way in which centrifugal force really helps to maintain the spinning of a top is, that when the body inclines or begins to fall in one direction, the motion in that direction continues until the point in describing its curve has forced itself under the bodv aoiain. At page 79, after “ increases f line 2\st. This truth is well exemplified by the pouring out of molasses or thick syrup : if the height of the fall be consi¬ derable, the bulky mass, which first escapes, is reduced, before it reaches the bottom, to a small thread; but the thread is moving with proportionate speed, for it fills the receiving vessel with singular rapidity. At page 82, after line Qth. It is shewn in a preceding paragraph, that a body falls jur times as far in two seconds as in one, although the velocity at the end of two seconds is only doubled. For tile same reason, a body shot upwards with double velo¬ city, rises four limes as far as if shot with a single velocity; if with triple velocity, it rises nine limes as far, and so forth.