PEOBLEMS WITH THE LEVER 103 



PROBLEMS WITH THE LEVER 



118. The seesaw board is one kind of lever ; the point of 

 support is called the fulcrum. 



119. The seesaw board will balance when the weight on 

 one end multiplied by its distance from the fulcrum equals 

 the product of the weight on the other end by its distance 

 from the fulcrum. 



EXERCISE 



1. John weighs 100 Ib. and sits 5 ft. from the fulcrum ; 

 where must Oscar, who weighs 80 Ib., sit, to make the see- 

 saw board balance ? 



2. Cyrus, who weighs 120 Ib., sits on a seesaw 6 ft. from 

 the fulcrum ; his sister, who weighs 60 Ib., sits 4 ft. from 

 the fulcrum on the same side. Their father sits on the other 

 end of the board 5 ft. 4 in. from the fulcrum. How much 

 does their father weigh if the seesaw balances ? 



100 Lb.X6 ===== 12 X 50 



jc 6in. -- 12 in. 



LEVER 



3. A man with a crowbar 6 ft. long places one end of it 

 under a stone 1 ft. from the fulcrum. If he weighs 180 Ib., 

 how many pounds of the stone can he lift ? 



4. A horse hitched to a doubletree, 18 in. from the clevis 

 that attaches it to a plow, exerts a pull of 150 Ib. Another 

 horse hitched to the other end of the doubletree, 20 in. from 

 the clevis, exerts a pull of how many pounds if both horses 

 pull evenly ? 



5. A team is hitched to a doubletree 4 ft. long. At what 

 point must the doubletree be attached to a plow so that one 

 horse will pull twice as much as the other ? 



