CHAPTER X. 

 FARM MECHANICS. 



Work. The word work is used in various senses. It 

 will here be used in its scientific sense that of moving 

 against resistance. The mere push or pull of a force 

 is not work; the point of application of the force must 

 move before work can be said to be done. A foot-pound 

 of work is done when a force of one pound moves its 

 point of application through a distance of one foot in 

 the direction of the force. 



501. How much work is done by a force of 20 pounds 

 when its point of application moves 30 feet in the direc- 

 tion of the force? 



Process: 20 X 30 = 600 foot-pounds of work. 



502. How much work is done when a 160-pound man 

 climbs to the top of a 40-foot windmill ? 



503. How much work is done when a 120-pound boy 

 walks up one flight of stairs to a second floor which is 10 

 feet above the first ? Ans. 1,200 foot-pounds. 



504. How much work does a 1,200-pound horse do in 

 walking up a hill 100 feet high ? 



505. The draft of (the force required to pull) a cer- 

 tain hand cart is 15 pounds. How much work does a boy 

 do in pushing it a mile? 



Process : 5,280 X 15 = 79,200 foot-pounds. 



506. How much work is done by a team in plowing 

 a furrow 40 rods long when the draft of the plow is 600 

 pounds ? 



149 



