1/2 MAN'S WAY OF HELPING HIMSELF 



exerted, and the distance covered, or that W force x dis- 

 tance. A man who raises 5 pounds a height of 5 f ee t does 



far more work than a 

 man who raises 5 ounces 

 a height of 5 inches, 

 but the product of force 

 by distance is 25 in each 

 case. There is difficulty 

 because we have not 

 selected an arbitrary 

 unit of work. The unit 

 of work chosen and in 

 use in practical affairs 

 is the foot pound, and 

 is defined as the work 



FIG. 116.- A traveling crane. done when a force of 



I pound acts through 



a distance of I foot. A man who moves 8 pounds through 

 6 feet does 48 foot pounds of work, while a man who moves 



FIG 117. A farm engine putting in a crop. 



8 ounces (| pound) through 6 inches (\ foot) does only one 

 fourth of a foot pound of work. 



