Farrow's military encyclopedia : a dictionary of military knowledge . he tension of the power, P. the weightmust be four times the power. In this system theweight is many times the power as thereare folds in the string, the folds being counted be-tween the two blocks. In tlie third system Fig. 17,each pulley hangs by a separate string, and the endof each string is attached to the weight, the wholebeing suspended from a fixed support. The tensionm the string passing over the first pulley at the bot-tom is the power, P ; the tension in the string pass-ing over the next pulley is 2 P: t
Farrow's military encyclopedia : a dictionary of military knowledge . he tension of the power, P. the weightmust be four times the power. In this system theweight is many times the power as thereare folds in the string, the folds being counted be-tween the two blocks. In tlie third system Fig. 17,each pulley hangs by a separate string, and the endof each string is attached to the weight, the wholebeing suspended from a fixed support. The tensionm the string passing over the first pulley at the bot-tom is the power, P ; the tension in the string pass-ing over the next pulley is 2 P: the tension inthe string passing over the third pulley from thebottom is 4 P ; and so on. Thus it is when threepulleys are arranged in this manner, W is sup-ported by P -f 2 P -f- 4 P, that is, by 7 P, and MECHANICAL POWERS. 305 MECHANICAL P0WEH8. therefore tlio wLi>,lit in exactly cqnnl to seventimes tlie power. The IlTect of iiny <iIIiit nimilMTiniiy he eiilculaled Himilurly. The tirst ihiiit; tliatstrikes (iiif (in (xiiiriiiienling with tlie piiMeys is tlie. principle of virtual velocities. Let us mal^e an ex- IHTimcnt with tlie first system, shown in Fii;. we liavB three movable puhcys, luiil we tinilthat a ]iower of 1 oz. halanees a weight of H oz. Triif:hut cm imtting the machine in action, we also liiHJthat wlien the weight is raised 1 ft. the power has tomove through 8 ft., so that what is gained in poweris lost in speod. and, as we said before, this is trueof every machine. We now come to consider the inclined |)lauc. Here
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Keywords: ., bookcentury1800, bookdecade188, booksubjectmilitaryartandscience
