Reseña del editor
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1890. Excerpt: ... 379. What is the origin of the dimensions of power? ML T T T 380. Show how the expression (XT'-'2) for the dimensions of acceleration is obtained. L T T T MOMENTS. 381. What does the term moment in such expressions as "moment of a couple," " moment of a magnet," " moment of a force," "moment of inertia," etc., signify? The importance or value of the subject referred to. 382. Suppose forces of 8 and 2 to be applied respectively 1 and 4 units of distance from the fulcrum of a lever: do the numbers 8 and 4 express the relative value of these forces? 383. (a) Suppose a rod CD, capable of turning about the fixed point D, to be acted on by a force F; the tendency of the force to turn the rod about D will depend on what two quantities? (b) In what two ways may this tendency be doubled? (c) How would you calculate the moment of the force? 384. When any number of forces are in equilibrium, what is the algebraic sum of their moments? 385. If three men support a triangular platform at its three corners, what portion of the weight will each bear? 386. What is the moment of a couple? It is the product of one of the forces multiplied by the perpendicular distance between the lines representing the directions in which the two forces act. 387. Show that the sensitiveness of a balance is increased by lengthening its arms. 388. Show that the moment of a force is greater in shutting a door when applied at the handle than if applied near the hinge. 389. Show that doubling the distance of a force from the fulcrum is as good as doubling the force itself. 390. State how, by means of a lever, a force of 8 lbs. can produce equilibrium with a force of 96 lbs. 391. A horizontal bar is supported at its center, but is free to rotate about its support; a weight of 10 lbs. is applied t...
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