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Rotating a curve y=x^1/2 ,[under root x] , about x-axis produces head light as shown. 1)What is the area of disc at any x? 2What is the volume of this head light where x varies from 0 to 2?

Rotating a curve y=x^1/2 ,[under root x] , about x-axis produces  head light as shown. 
 
1)What is the area of disc at any x?
2What is the volume of this head light where x varies from 0 to 2? 

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1 Answers

Venkat
273 Points
5 years ago
1.Area of disc = area of circle = pi*r^2 =
\\A=\pi r^2 \\A=\pi (\sqrt{x})^2 \\A=\pi x
 
  1. consider a small flat disc. The volume of such disc would be
\\V=\pi r^2\times thickness \\ V=\pi (\sqrt{x})^2dx
Add these volumes to get the final volume
\\V=\int_{0}^{2}\pi (\sqrt{x})^2dx \\V=\int_{0}^{2}\pi xdx \\ \\V={\frac{\pi}{2} (x^2)}_{0}^{2} \\ \\V={\frac{\pi}{2} (4)} \\ \\V={2\pi}
 

 

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