156 MAWS WAY OF HELPING HIMSELF 



knapsack twice the distance, say to your shoulders instead 

 of to the level of the table, you would do twice the work, 



because while you would 

 exert the same force you 

 would. continue it through 

 double the distance. 



Lifting heavy weights 

 through great distances is 

 not the only way in which 

 work is done. Painting, 

 chopping wood, hammer- 

 ing, plowing, washing, 

 scrubbing, sewing, are all 

 forms of work. In painting, 

 the moving brush spreads 



FIG. 94. Crude method of farming. ., r 



paint over a surface; in 



chopping wood, the descending ax cleaves the wood asunder ; in 

 scrubbing, the wet mop rubbed over the floor carries dirt away ; 

 in every conceivable form of work, force and motion occur. 



A man does work when he walks, a woman does work 

 when she rocks in a chair although here the work is less 

 than in walking. On a windy day the work done in walking 

 is greater than normal. The wind resists our progress, and 

 we must exert more force in order to cover the same distance. 

 Walking through a plowed or rough field is much more tiring 

 than to walk on a smooth road, because, while the distance 

 covered may be the same, the effort put forth is greater, and 

 hence more work is done. Always the greater the resistance 

 encountered, the greater the force required, and hence the 

 greater the work done. 



The work done by a boy who raises a 5-pound knapsack to 

 his shoulder would be 5x4, or 20, providing his shoulders 

 were 4 feet from the ground. 



