What is the Volume to Surface Area Ratio of a Sphere?

AI Thread Summary
The volume to surface area ratio of a sphere can be calculated using the formulas for volume, V = (4/3)πr^3, and surface area, A = 4πr^2. The ratio V/A simplifies to r/3, indicating that the ratio depends on the radius of the sphere. The discussion highlights a common confusion in calculating this ratio, but the solution is straightforward once the formulas are applied. Understanding this ratio is essential for various applications in geometry and physics. The conversation emphasizes the simplicity of the calculation once the correct approach is recognized.
scupydog
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hi all could anyone tell me the ratio of the volume of a shere to the surface area of the same sphere, i can't seem to sort this one out in my head, thx
 
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V=(4/3)*pi*r^3, A=4*pi*r^2. What's so hard about finding V/A?
 
oh yeah doh, thanks dick
 
I tried to combine those 2 formulas but it didn't work. I tried using another case where there are 2 red balls and 2 blue balls only so when combining the formula I got ##\frac{(4-1)!}{2!2!}=\frac{3}{2}## which does not make sense. Is there any formula to calculate cyclic permutation of identical objects or I have to do it by listing all the possibilities? Thanks
Since ##px^9+q## is the factor, then ##x^9=\frac{-q}{p}## will be one of the roots. Let ##f(x)=27x^{18}+bx^9+70##, then: $$27\left(\frac{-q}{p}\right)^2+b\left(\frac{-q}{p}\right)+70=0$$ $$b=27 \frac{q}{p}+70 \frac{p}{q}$$ $$b=\frac{27q^2+70p^2}{pq}$$ From this expression, it looks like there is no greatest value of ##b## because increasing the value of ##p## and ##q## will also increase the value of ##b##. How to find the greatest value of ##b##? Thanks
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