VDU_Physics_2_007  
 

 

Solved University-Physics Problems

Physics 2.-  Fluid Dynamics

 

Javier Montenegro Joo

jmj@VirtualDynamics.Org

 

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  Fluid Dynamics.-  
  [01234]  
 

(1) Consider an open tank containing water until a height  H. A small hole is open in its lateral wall at a height  h  from the bottom.  Determine: (a) the speed of water escaping through the hole (b) the horizontal range of the escaping water. 

Solution.-

The descent velocity of the water in the tank is so small compared with the escape velocity through the lateral hole, that the former may be considered zero.   Since tank is open at its top and at the hole, at both places the pressure is that of the atmosphere. Surface of the water: subscript 1.         Hole in tank wall: subscript 2

 
  [56789]  
 

(2) A liquid whose density is half that of the water travels along a pipe of circular section, at 1.5 m/s and under a pressure of 25 kPa. Four meters ahead the pipe narrows to one-half of its original diameter. Determine the pressure in the narrow part of the pipe.

Solution.-

Considering the sketch below, apply Bernoulliís law to points (1) and (2):

 
     
 

(3)    A large closed tank contains liquid of density D up to a certain height h.  Inside the tank and above the liquid the air pressure is two times greater than the atmospheric pressure. Determine: (a) the pressure at the bottom of the tank (b) the speed with which would escape the liquid to the atmosphere, if a small hole were opened in the bottom of the tank. 

Solution-

 
 

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