POWER OF WORK 



pounds through 6 feet 

 does 48 foot pounds of 

 work, while a man who 

 moves 8 ounces (J 

 pound) through 6 

 inches (J foot) does 

 only one fourth of a 

 foot pound of work. 



The power or the 

 speed with which work 

 as done. A man can 

 load a wagon more 

 quickly than a growing 

 boy. The work done 



by the one IS equal to FlG " '78.- The typewriter is a compound machine. 



the work done by the other, but the man is more powerful and 

 does the work in a shorter time. An engine which hoists a 50- 

 pound weight in I second is much more powerful than a man 

 who requires 50 seconds for the same task. In estimating the 



'"<./ t >./**> d&L&^m > value of a working agent, 



whether animal or me- 

 :hanical, we must con- 

 sider not only the work 

 done, but the speed with 

 which it is done. 



The rate at which a 

 machine is able to ac- 

 complish a unit of work 

 is called power, and the 

 unit of power custom- 

 arily used is the horse 

 power. Any power which 

 FIG. 179. A traveling crane. Can do 550 foot pounds 



INTRO. TO SC. 20 



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