What is the cross section area of the water?

yy205001
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what is the cross section area of the water??

Homework Statement


Determine an expression for the cross sectional area A of the fluid in the tank as a function of D and H.


Homework Equations


A=pi*r2

The Attempt at a Solution


i try to let the radius equal to the height but then the fluid's height goes lower, it doesn't form a circle anymore. So i have no ideas how to do this.Please help.
 

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yy205001 said:

Homework Statement


Determine an expression for the cross sectional area A of the fluid in the tank as a function of D and H.


Homework Equations


A=pi*r2

The Attempt at a Solution


i try to let the radius equal to the height but then the fluid's height goes lower, it doesn't form a circle anymore. So i have no ideas how to do this.Please help.

What is the shape of the tank? In your drawing, the cross-section is half a circle, but is the tank spherical or cylindrical or what? To get an expression for the cross-sectional area of the water, you need to know the shape of the tank.
 


I believe the tank is a half sphere? So, the volume of the sphere is: \frac{2}{3}\pi r^3
 


Correction added.
sharks said:
I believe the tank is a half sphere? So, the volume of the hemi[/color]sphere is: \frac{2}{3}\pi r^3

Nothing in the OP's post says anything about the actual shape of the tank.
 


If you click on the attached picture in the first post, it does say "hemispherical" in the lower-right corner. In that case, H= r (radius if sphere) and D = 2r (diameter).
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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