12
1 We are using the term “torque” to mean the axial vector N=r × F, and “moment” to mean the the scalar quantity N · n which is the component of N in a specified direction n.
2 The vector ljdrawn from the point j will intersect the axis AX. This can be seen by writing rj=rjer, pj=pjeφ, using the spherical coordinate system so that ij=rj × pj= –rjpjeθ. See Sec. 6.8.2 and Eq. (6.53). The vector –eθdrawn from the point j would pass through the axis AX.
3This statement is approximately true. The combined gravitational pull of the Sun and the Moon creates a small torque about the Earth's centre. This causes a small precession of the axis of the Earth, the period of which is about 26, 000 years. As a consequence the Earth's rotation axis will not ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access