THE WHEELBARROW AS A LEVER 295 



is compensated for by the greater distance through which it 

 acts. 



At first sight it seems as though the man's work were done 

 for him by the machine. But this is not so. The man must 

 lower his end of the lever 4 feet in order to raise the bowlder 

 6 inches out of the ground. He does not at any time exert a 

 large force, but he accomplishes his purpose by exerting a 

 small force continuously through a correspondingly greater 

 distance. He finds it easier to exert a force of 200 pounds con- 

 tinuously until his end has 

 moved 4 feet rather than to 

 exert a force of 1600 pounds 

 on the bowlder and move it 

 6 inches. 



By the time the stone has 

 been raised, the man has done 

 as much work as though the 

 stone had been raised di- 

 rectly. But his inability to 



put forth sufficient muscular 



f . . t ,, j. ^&wntw<" -'."^71... '/// 



force to raise the bowlder di- 



. .. , . FIG. 159. The wheelbarrow lightens labor. 



rectly would have made im- 

 possible a task which was easily accomplished when by means 

 of the lever he extended his small force through a greater 

 distance. 



The wheelbarrow as a lever. The principle of the lever 

 is always the same ; but the relative position of the important 

 points may vary. For example, the fulcrum is sometimes at 

 one end, the force at the opposite end, and the weight to be 

 lifted between them. 



Suspend a stick with a hole at its center as in Figure 158, and 

 hang a 4-pound weight at a distance of I foot from the fulcrum, 

 supporting the load by means of a spring balance 2 feet from 



