Calculating Force on the Bottom of a Cylinder in Fluid Physics

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Homework Help Overview

The discussion revolves around calculating the force acting on the bottom of a cylinder filled with water, considering both static and dynamic pressures. The problem involves fluid physics concepts, particularly related to forces and pressures in a fluid system.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants explore the relationship between static and dynamic pressures, questioning whether both should be included in the force calculation. The original poster expresses uncertainty about the necessity of dynamic pressure in the context of the problem.

Discussion Status

Some participants have provided insights regarding the inclusion of dynamic pressure in the force calculation, suggesting that it is essential for an accurate assessment. There is an ongoing exploration of how static and dynamic pressures relate to the overall force, with some participants questioning the implications of time and water consumption on the calculations.

Contextual Notes

The problem is framed within specific parameters, including the height of the water, the diameter of the cylinder, and the rate of water flow. There is a noted concern about the assumptions regarding the behavior of water as it enters the cylinder and its effect on the force calculation.

Yegor
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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!
 
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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.
 
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?
 
Can anybody help? please
 

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