184 EXAMPLES. 



23. A plane area moves perpendicularly through water 

 in which it is deeply imbedded. Find the resistance per 

 square foot at a speed of 10 miles an hour. Am. 269 Ibs. 



24. A stream of water delivering 100 cubic feet per min- 

 ute, at a velocity of 15 feet per second, strikes an indefinite 

 plane normally. Find the pressure on the plane. 



Ans. 48.6 Ibs. 



25. If a stream of water, the area of whose cross-section 

 is 64 square inches, impinges with a velocity of 40 feet per 

 second against the convex surface of an immovable cone, in 

 the direction of its axis, the vertical angle of the cone 

 being 100, find the impulse. Ans. 492.16 Ibs. 



26. A stream of water, the area of whose cross-section is 

 40 square inches, delivers 5 cubic feet per second, and strikes 

 normally against a plane surface, which moves away with a 

 velocity of 12 feet per second. Find (1) the impulse, (2) 

 the maximum work, and (3) the maximum impulse. 



Ans. (I) 58.125 Ibs.; (2) 784.688 ft. -Ibs.; (3) 87.19 Ibs. 



