MECHANICS OF LIQUIDS . 85 



9. The cork of a life preserver weighs 19 Ibs. What is the 

 volume in cubic inches? The specific gravity of cork is 0.25. 



10. Elevators are often run by water pressure obtained from the 

 local water system. If the pressure on the main is 55 Ibs. and the 

 diameter of the plunger of an elevator is 11 in., how heavy a load 

 can the elevator lift if the friction loss is 30%? 



11. Soundings at sea are made by lowering a form of pressure 

 gauge. If a pressure gauge reads 65 Ibs., what is the depth? (Con- 

 sider the density of sea water 1.026.) 



12. What is the weight of a cylindrical piece of lead 4 ft. long 

 with a diameter of 3 in. ? The specific gravity of lead is 11.4 and 

 the weight of a cubic foot of water is 62.5 Ibs. 



13. What is the weight of concentrated sulphuric acid (specific 

 gravity 1.84) contained in a cylindrical jar 8 in. in diameter and 

 lYi in. high? A cubic foot of water weighs 62.5 Ibs. 



14. Determine the weight of gasolene in a rectangular tank 

 3 ft. 7 in. X 2 ft. 2 in. X 1 ft. 8 in., if the specific gravity is .7 and 

 a cubic foot of water is equal to 62.5 Ibs. 



15. The inside diameter of a lead pipe is 1 in. and the thickness 

 of pipe is % in. How many pounds in a foot of pipe? The specific 

 gravity of lead is 11.4 and a cubic foot of water weighs 62.5 Ibs. 



16. What are some of the principles of science underlying the 

 hydraulic machine? 



17. What are some of the uses of hydraulic machines? 



18. (a) What is the weight of a cubic inch of water if a cubic 

 foot weighs 62.5 Ibs. 



(b) How may the weight of a cubic inch of a substance be de- 

 termined, if the specific gravity of the substance is known? 



19. In making solder (composed of lead and tin) , the tin melts 

 first and then floats on top. Why? 



