IN POPULAR PHYSICS. 25 



10. What weight could be lifted with a single horse 

 power (3 3 ,OOO Ibs. one foot high per minute) acting on a 

 system of pulleys shown in Fig. 62 ? 



"W = 33,000 x2x2x2x2= 528,000 Ibs. 



11. What distance should there be between the threads 

 of a screiv, that a P of 25 lbs. 9 acting on a handle 3 ft. 

 long, may lift 1 ton weight? 



P : W : : Interval : Circumference. 



25 Ibs. : 2,000 Ibs. : : x : 72 in. x 3.1416. 



x = 2.83 -in. 



12. How high could a P of 12 Ibs., moving 16 ft. along 

 an inclined plane, lift a W of 96 Ibs. ? 



P : W : : height : length. 



12 Ibs. : 96 Ibs. : : x : 16 ft. 



X = 2 ft. 



13. I wish to roll a barrel of flour into a wagon, the 

 booc of which is 4 ft. from the ground. I can lift but 24= 

 Ibs. How long a plank should I get ? 



P : W : : height : length. 

 24 Ibs. : 196 Ibs. : : 4 ft. : x = 32f ft. 



14. What Wean be lifted with a P of 1OO Ibs. acting 

 on a screw having threads 1 in. apart t and a handle 4 ft. 



long? 



P : "W : : Interval : Circumference. 



100: x:: 1 : 4x12x3.1416 

 x = 15,079.68. 



15. What is the object of the balls often cast on the ends 

 of the handle of the screw used in presses for copying let" 

 ters ? 



By their momentum they make the motion more uniform 

 and continuous. 



16. In a steelyard 2 ft. long, the distance from the 

 weight-hook to the fulcrum-hook is 2 in. How heavy a 

 body can be weighed with a 1 Ib. weight ? 



24 in.- 2 in. = 22 in. 1 Ib. x 22 = 22 Ibs. = P. 

 22 Ibs. -*-2= 11 Ibs. =W. 



