Conservation of Energy 



61 



If you wanted to make the pail move farther and faster 

 than your hand, would you put your hand nearer to the 

 fulcrum than the pail is, or farther from the fulcrum than 

 the pail? If you \vanted to move the pail with the least 

 effort, where w r ould you put your hand? 



Experiment 20. Use a pair of long-bladed shears and 

 fold a piece of cardboard once to lie astride your own or 

 some one else's finger. Put the finger, protected by the 

 cardboard, between the two points of the shears. Then 

 squeeze the handles of the shears together. See if you can 

 bring the handles together hard enough to hurt the finger 

 between the points. 



Now watch the shears as you open and close the blades. 

 Which move farther, the points of the shears or the handles? 

 Which move faster? 



Next, put the finger, still protected by the cardboard, 

 between the handles of the shears and press the points to- 

 gether. Can you pinch the finger this way harder or less 

 hard than in the way you first tried? 



FIG. 29. You cannot pinch hard enough this way to hurt. ' 



