Spinning Tops And Gyroscopic Motions PDF Download

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1914 edition. Excerpt: ...that so long as the axle lies North and South and is horizontal, it is not affected by the action of gravity. If for any reason it is displaced from the meridian (but not so far as a West-East position), the rotation of the earth still causes a dip, and therefore the gravity couple comes into play, restoring CN to the North-South position; while at the same time a couple is produced by air-currents which eliminates dip as CN approaches the meridian. A mathematical discussion of the forces called into play is given in Appendix V. CHAPTER VI. STEADY MOTION OF A TOP. 75. The student is reminded at the commencement of this chapter that, when a solid body is under consideration, (i) Angular velocity about any line means total angular velocity--not relative to some moving plane, unless this is expressly stated. (ii) Angular velocity about a line which is moving means (total) angular velocity about the line fixed in space, with which the moving line happens to be coinciding at the instant in question. 76. In the preceding chapter the bodies whose rotation we have discussed have been symmetrical bodies, as, for example, a fly-wheel; and all the rotations have been about an axis of symmetry, i.e. the axle. If the axis were not an axis of symmetry, an angular velocity about this axis would in general involve angular momentum (about this axis, and also) about the two axes perpendicular to it, as is shown in the next article. In this chapter we propose to discuss the equations of motion of an ordinary spinning top, in which case it is clear that only the axle of the top is an axis of symmetry, and any other axis is not. But we shall see in Art. 79 that, since the top is a solid of revolution, any axis perpendicular to the axle of the top is the same...