. The elements of railroad engineering . 2 lb9.\ ELEMENTARY MECHANICS. 345. Fig. 151. Case II.—In Fig. 151, the power is supposed to act par-allel to the base for any position of IV, the pulley being shifted up and down;therefore, while IV ismoving from the levela c to d, or through theheight c d of. the in-clined plane, P willmove a distance down-wards, relative to theaxis of the pulley, equalto the length of thebase a c. Hence, when the power acts parallel to the base,IV X licigJit of the inclined plane = P x length of base. If the length of the base is 40 feet, and the height of theinclined


. The elements of railroad engineering . 2 lb9.\ ELEMENTARY MECHANICS. 345. Fig. 151. Case II.—In Fig. 151, the power is supposed to act par-allel to the base for any position of IV, the pulley being shifted up and down;therefore, while IV ismoving from the levela c to d, or through theheight c d of. the in-clined plane, P willmove a distance down-wards, relative to theaxis of the pulley, equalto the length of thebase a c. Hence, when the power acts parallel to the base,IV X licigJit of the inclined plane = P x length of base. If the length of the base is 40 feet, and the height of theinclined plane is 20 feet, I^X 30 = /^ X 40, and 1 pound atP will balance 2 pounds at W. Case III.—For no rule can be ratio of the powerto the weight must bedetermined for everyposition of IF by meansof the triangle or paral-lelogram of forces. This case will be ex-plained by means of an example, as it affords a • fig. 152. splendid illustration of the principle of resolution of forces. Example.—In Fig. 153, a body ^ is shown resting on an inclinedplane


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