EXAMPLES. 239 



14. What is the discharge per second through a pipe 48 

 feet long and 2 inches in diameter, under a head of 5 feet ? 



Suo. Assume / = .02, and obtain from (8) of Art. 106, v = 6.6 

 feet, and therefore (Sch. of Art. 105), /= .0211, which in (8) of Art. 

 106 gives v = 6.52 feet. .-. etc. 



Ans. 245.8 cubic inches. 



15. What must be the diameter of a pipe 100 feet long, 

 which is to discharge one-half of one cubic foot of water per 

 second under a head of 5 feet ? Ans. 3.82 inches. 



See remark in Art. 107. 



16. If the diameter of one portion of the compound pipe 

 (Fig. 55) is twice that of the other, and if the velocity of 

 the water in the larger is 10 feet, find (1) the coefficient of 

 resistance, and (2) the loss of head at the sudden enlarge- 

 ment, the water flowing from the small pipe into the large 

 one. Ans. (1) 4 ; (2) 13.95 feet. 



17. A pipe 2 inches in diameter is suddenly enlarged to 

 3 inches. If it discharge 100 gallons per minute, the water 

 flowing from the small pipe into the large one, find (1) the 

 coefficient of resistance, and (2) the loss of head at the sud- 

 den enlargement. Ans. (1) 1.59; (2) 8 inches. 



18. In the last example, if the water moves in the reverse 

 direction, find the loss of head caused by the sudden con- 

 traction, assuming the coefficient of contraction to be 0.66. 



Ans. 7 inches. 



19. A pipe contains a diaphragm with an orifice in it, the 

 area of which is one-fifth the sectional area of the pipe. 

 Find the coefficient -of resistance of the diaphragm, assum- 

 ing the contraction on passing through the orifice the same 

 as that at efflux from a vessel through a small orifice in a 

 thin plate. Ans. 46. 



20. A horizontal pipe 30 feet long is suddenly enlarged 

 from 2 inches to 3 inches, and then suddenly returns to its 

 original diameter ; the length of each section is 10 feet. If 



