Exercises on Mechanics and Natural Philosophy, Or, an Easy Introduction to Engineering, for the Use of Schools and Private Students; Containing Various Applications of the Principle of Work - The Theory of the Steam Engine, with Simple (Paperback)

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. 1853 edition. Excerpt: ... wedge. However, it is necessary to observe, that the astonishing power of the wedge, as usually employed, is chiefly resolvable into the force of impact, which will be considered in a future article. Ex. 1. The length of a wedge = 1-5 ft., the thickness = 2 ft., the pressure applied = 100 lbs.; required the weight that would be raised. When the pressure applied has moved through the length of the wedge, we have, Work applied = 100 x 1/5; Work done = W x-2. /. W x-2 = 100 x 15, and W = 750 lbs. Ex. 2. Required the same as in the last example, when the length is 2 ft., the thickness-4 ft., and the pressure applied 400 lbs. Ans. 2000 lbs. The Screw. 44. In this mechanical power the pressure applied moves in a circle whose radius is the length of the lever, or arm of the screw, whilst the direction in which the work is done, is a right line. Ex.. The lever of a simple screw is 2 feet, the thickness of the thread-2 feet; if a pressure of 100 lbs. be applied to the lever, what pressure will be produced on the press board? Here in one turn of the lever, the press board is moved over the distance between the threads of the screw..-. Space moved over by P, in 1 revo. = 4 x 3-1416. W=-2 Work of P in 1 revo. = 4 x 3-1416 X 100. W = Wx-2. /. W x-2 = 4 X 3-1416 x 100, and W = 6283 lbs. Obs. The equation here obtained shows that the efficacy of the screw is obtained by increasing the length of the lever, or by decreasing the thickness of the threads. Ex. 2. Required the same as in the last example, when the thickness of the threads is in., and the pressure applied to the lever is 60 lbs. Ans. 18095 lbs. Ex. 3. Required the advantage of the power in the last example. Ans. 301. Ex. 4. The lever of a screw is 3 ft., and the thickness of...