. Natural philosophy. including statics, hydrostatics, pneumatics, dynamics, hydrodynamics, the general theory of undulations, the science of sound, the mechanical theory of music, etc. : designed for the use of normal and grammar schools, and the higher classes in common schools . ystem of pulleys represented in Fig. U,what power will balance a weight of 4500 lbs., when there are4 movable pulleys ? W = 4500 and n — i. * , „_ TT 4500 4500 ,.^ .. Then P ?=. — =. = =: oo5 lbs. Ans. 3» 31 81 y Example 68.—In such a system when there are 6 movablepulleys, what weight will a powe
. Natural philosophy. including statics, hydrostatics, pneumatics, dynamics, hydrodynamics, the general theory of undulations, the science of sound, the mechanical theory of music, etc. : designed for the use of normal and grammar schools, and the higher classes in common schools . ystem of pulleys represented in Fig. U,what power will balance a weight of 4500 lbs., when there are4 movable pulleys ? W = 4500 and n — i. * , „_ TT 4500 4500 ,.^ .. Then P ?=. — =. = =: oo5 lbs. Ans. 3» 31 81 y Example 68.—In such a system when there are 6 movablepulleys, what weight will a power of 10 lbs. support? P z=i 10, and n = IF = P x 3 = 10 x 3^ = 10 x 729 = 7290 lbs. Ans. EXERCISE. G9. In the system of pulleys represented in figure 11, there are movable pulleys; what weight may be supported by a power of 10 Ans. 2430 lbs. 70. In such a system there are 7 movable pulleys and the weightis 24057 lbs. Piequired the power. Ans. 11 lbs. 71. In such a system there are 9movable pulleys — throughhow many feet must thepower descend in order toraise the weight 10 feet? Ans. 19G830feet. 112. If the lines of direc-tion of the power and weightmake with one another anangle greater than 120°, thepower will require to be greater. 38 THE INCLINED PLANE. [Aktb. 113-117 than the weight; and as this angle approaches 180°, thedifference between the power and weight will approachGC. Hence it is impossible for any power P, howevergreat, applied at P, to pull the cord J.^ (7 mathematicallystraight, and that however small the weight TFmay be. THE INCLINED PLANE. 113. The Inclined Plane is regarded m mechanicalscience as a perfectly liard, smooth, inflexible plane, in-clined obliquely to the weight or resistance. 114. There are two ways of indicating the degree oiinclijiation of the inclined plane: 1st. By saying it rises so manv feet, inches, &c., in acertain distance. 2nd. By describing it as rising at some stated anglewith the horizon. 115. I
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