Lessons in elementary physics / by Balfour Stewart.

  • Balfour Stewart
Date:
1895
Catalogue details

Licence: Public Domain Mark

Credit: Lessons in elementary physics / by Balfour Stewart. Source: Wellcome Collection.

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    rotation, a particle at the circumference, such as A, is at any moment moving in the direction of a tangent to the circle at that point ; that is to say, in the direction of the arrow head, and if left free to itself it would, in virtue of the first law ot motion, continue to move in this direction A B ; but it is constrained, by the cohesion of the other particles to which it is attached, continually to vary its direction. If, however, the rotation is very rapid, the force of cohe- sion may be insufficient to accomplish this, and the con- sequence will be that the par- ticles at the circumference will leave the system, and be scattered about. In the case of a sling, the force which keeps the stone attached to the sling is intentionally with- drawn at the right moment, and the consequence is that the stone, in virtue of the first law of motion, perseveres in that path which it was following when the central force was withdrawn. The property enunciated by the first law is usually called inertia, and implies that matter is passive or has no power in itself to change its state whether of rest or motion. A B Lesson III.- .Second Law, First .Statement: Action ok A Single Force on a Moving Body. 18. statement of Second Law.—We now proceed to the second law of motion, which may be stated as follows :. If any number of forces act together upon a moving body, each force generates the same velocity as it would generate if it acted singly upon the body at rest. For the sake ol clearness we mav diviile this statement into two, aiul consider— (1) 'I he action of a singie lorce on ,a moving hotly ; (2) The action of several forces together upon :i body. Let us at present consider the action of ;i on a moving hotly. .Suppose, for inst.ance, lh.it single force in a railw.ay
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