. A text book of elementary mechanics, for the use of colleges and schools. alance it ? 5. The length of a Danish steelyard is 30 in., its weight is4 lbs., and acts at a point 3 in. from one end; a body weighing12 lbs. hangs at the other end: Where is the fulcrum ? 6. The length of a Danish steelyard is 28 in., its weight is3 lbs., acting at a point 4 in. from one end: (a) Where is the (b) the II. Wheel and Axle. 202. The Wheel and Axle, in its simplest form,consists of two cylinders of different sizes, rigidly con-nected and turning about a common axis; the larger iscalled
. A text book of elementary mechanics, for the use of colleges and schools. alance it ? 5. The length of a Danish steelyard is 30 in., its weight is4 lbs., and acts at a point 3 in. from one end; a body weighing12 lbs. hangs at the other end: Where is the fulcrum ? 6. The length of a Danish steelyard is 28 in., its weight is3 lbs., acting at a point 4 in. from one end: (a) Where is the (b) the II. Wheel and Axle. 202. The Wheel and Axle, in its simplest form,consists of two cylinders of different sizes, rigidly con-nected and turning about a common axis; the larger iscalled the wheel, and the smaller the axle. The poweris applied to the end of the rope wound about the wheel,and the weight is raised by a rope wound upon the is seen in Fig. 146. 216 STATICS. [203. 203. Suppose the power and weight to act in the sameplane perpendicular to the axis, as in Fig. 147. Treatedin this way, it is essentially a form of lever, the fulcrumbeing at F; and in case of equilibrium the condition(156) will hold good that the algebraic sum of the mo-. Fia 146. Fig. 147. ments of P and W about the axis must be equal to zero. That is, = If AF = R, and BF = r, then PW R> or- The Poiver is to the Weight as the radius of the axle isto the radius of the wheel. 204. Since the power, if applied by a rope as here,must always act at right angles to the radius of thewheel, the relation given above holds good whatever thedirection of P. The pressure upon the axle, however,will vary: if P and W are parallel and in the same direc-tion, it is equal to their sum: if in opposite directions, 207.] WHEEL AND AXLE. 217 to their difference; and in other cases it is to be obtainedby the parallelogram of forces. 205. The thickness of the rope is here speaking, half of this thickness should be addedto each of the radii. As the weight is raised, and itsrope consequently wound up on the axle, thus increasingits radius, and also that of the power is u
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectmechanics, bookyear18
