498 



GENERAL SCIENCE 



8. What class of lever is a pair of plyers? 



9. Tell what class of levers the following are and why; 



(1) Can opener. 



(2) Nut cracker. 



(3) Lemon squeezer. 



(4) Potato masher. 



(5) Door. 



(6) An oar when one is rowing a boat. 



lifted 



FIG. 379. What class of lever is the FIG. 380. 



paddle of a canoe? What class of 

 levers are the fingers on the strings 

 of the banjo? 



(7) An oar after being pulled out of the water and 



up preparatory to taking another stroke. 



(8) A knife. 



(9) A fork. 



(10) Fire tongs. 



(11) Spoon. 



(12) Sheepshears. 



(13) Typewriter key. 



(14) Piano key. 



(16) Arm. 



(17) Jaws. 



10. Why is a finger more likely to be 

 crushed if caught in the door near the hinge than near the latch? 



