Mechanics of engineeringComprising statics and dynamics of solids: and the mechanics of the materials of constructions, or strength and elasticity of beams, columns, arches, shafts, etc . ating ds, we have, dh __ c sin fi cos a # _ c sin yff cos a dx ~ r cos (fi — a) /* cos (/? — «)* 68. When the acceleration of the parts of the mechanism isnot practically zero, 2(Pdu) will not = 0, but a function ofthe masses and velocities to be explained in the chapter onWork, Energy, and Power. If friction occurs at moving joints,enough free bodies should be considered that no free bodyextend beyond such a
Mechanics of engineeringComprising statics and dynamics of solids: and the mechanics of the materials of constructions, or strength and elasticity of beams, columns, arches, shafts, etc . ating ds, we have, dh __ c sin fi cos a # _ c sin yff cos a dx ~ r cos (fi — a) /* cos (/? — «)* 68. When the acceleration of the parts of the mechanism isnot practically zero, 2(Pdu) will not = 0, but a function ofthe masses and velocities to be explained in the chapter onWork, Energy, and Power. If friction occurs at moving joints,enough free bodies should be considered that no free bodyextend beyond such a joint; it will be found that this frictioncannot be eliminated in the way in which T and HP were, in§65. 69. Additional Problems; to be solved by virtual 1.—Find relations between the forces acting on astraight lever in equilibrium; also, on a bent lever. Problem 2.—When an ordinary copying-press is in equilib-rium, find the relation between the force applied horizontallyand tangentially at the circumference of the wheel, and thevertical resistance under the screw-shaft. 72 MECHANICS OF ENGINEERING. CHAPTER III. CURVILINEAR MOTION OF A MATERIAL Fig. 76. [Motion in a plane, only, will be considered in this chapter.] 70. Parallelogram of Motions.—It is convenient to regardthe curvilinear motion of a point in a plane as compounded, ormade up, of two independent rectilinear motions parallelrespectively to two co-ordinate axes X and Y, as may be ex-plained thus: Fig. 76. Consider thedrawing-board CD as fixed, and let thehead of a T-square move from Atoward B along the edge according toany law whatever, while a pencil movesfrom M toward Q along the blade. Theresult is a curved line on the board, whoseform depends on the character of the two X and Y component motions, as they may be called. Ifin a time tx the T-square head has moved an Xdistance = MB,and the pencil simultaneously a Y distance = MP, by com-pleting the parallelogram on these lines
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectenginee, bookyear1888
