Fluid physics problem help

  • Thread starter Yegor
  • Start date
  • #1
147
1
I have the next problem:
Water is falling from the H=1 m into the cylinder.
Diametr of the culinder d=20 cm
Q=dV/dt=100 (cm^3)/s (consumption of the water).
I have to calculate force, which acts on the bottom of culinder in the end of 30nd second.

I can't believe, that it is simply F=m*g (m=density*V; V=Q*t)! (here V- volume)
Should I also take into acount dinamic pressure? Pdin=density*(v^2)/2; (here v-velocity) v=sqrt(2*g*H)
F=m*g+pdin*S (S=pi*d^2/4 - area)
Help me please!
 

Answers and Replies

  • #2
dextercioby
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Of course u'd need to include the force exerted by dinamical pressure.If u didn't,then the water would not be pouring into the cylinder,but instead being there motioness.

Daniel.
 
  • #3
147
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Ok.
In this way i receive:
Pstatic=density*g*h1 (h1 - height of the water in the culinder)
Pdinamic = density*(v^2)/2=desity*g*(H-h1) (From H falls the water)
P=Pstatic+Pdin= density*g*H
So it does not depend on the time and consumption of the water!!
Is it really correct?
 
  • #4
147
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Can anybody help? please
 

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