. A text book of elementary mechanics, for the use of colleges and schools. e string (orthrust of the prop), and its moment is ; the weight is that ofthe bar acting at its centre of gravity B, and its moment is value of P, derived from the equation RAF= , will give the tension of the string (or thrust of the prop) neededjust to support the rod. 200 STATICS. [190. 190. The Lever on the Principle of Work. It has beenshown in Art. 179 that, in the case of every machine, iffriction and all other hurtful resistances are eliminated, = , p A W ~~ s or W = T- (^ Here s is the d
. A text book of elementary mechanics, for the use of colleges and schools. e string (orthrust of the prop), and its moment is ; the weight is that ofthe bar acting at its centre of gravity B, and its moment is value of P, derived from the equation RAF= , will give the tension of the string (or thrust of the prop) neededjust to support the rod. 200 STATICS. [190. 190. The Lever on the Principle of Work. It has beenshown in Art. 179 that, in the case of every machine, iffriction and all other hurtful resistances are eliminated, = , p A W ~~ s or W = T- (^ Here s is the distance through which the power acts,and A the distance through which the weight is a resistance (R) is overcome through a distance d,then - , P d m By the use of these equations the relation of the Powerto the Weight (or Resistance), when the Power raisesthe Weight uniformly, can be obtained. This value of P —r is the same as that deduced on condition of equilib-w rium, on the principles of statics. In the case of the lever, suppose (1) that the power. Fig. 135. always acts vertically (Fig. 135) and turns the leverfrom the position AB to that of AB\ then the effective 190.] LEVEE. 201 distance through which it acts is AC (~ s), and theheight through which the weight is raised is BD (= h).Therefore P^ ITD _ ITF BF W ZZ AC ZZ AF ~ AF; .-. = , as in Art. 186. (2) Suppose the power and resistance to act continu-ally at right angles, to the straight lever AB (Fig. 136)
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectmechanics, bookyear18
