Volume of solid revolving about y-axis

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SUMMARY

The volume of the solid generated by revolving the region bounded by the graph of y = x³ and the line y = x, between x = 0 and x = 1, about the y-axis can be calculated using the formula for volume of revolution. The correct approach involves integrating with respect to y, leading to the expression π∫[R(y)² - r(y)²] dy. The integration limits must be adjusted accordingly, and it is crucial to include π in the final calculation. The integration results in the volume being determined by evaluating the integral of the outer radius squared minus the inner radius squared.

PREREQUISITES
  • Understanding of calculus, specifically integration techniques.
  • Familiarity with the method of cylindrical shells for volume of revolution.
  • Knowledge of functions and their graphs, particularly polynomial functions.
  • Ability to manipulate and evaluate definite integrals.
NEXT STEPS
  • Study the method of cylindrical shells in detail.
  • Practice integrating functions with respect to y for volume calculations.
  • Explore the implications of changing limits of integration when switching variables.
  • Learn about the application of π in volume calculations for solids of revolution.
USEFUL FOR

Students studying calculus, particularly those focusing on volume of revolution problems, as well as educators teaching integration techniques in mathematics.

frumdogg
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Homework Statement


Find the volume of the solid generated by revolving the region bounded by the graph of
y = x3 and the line y = x,
between x = 0 and x = 1,
about the y-axis.


Homework Equations



\pi\overline{1}\int\underline{0}[R(x)^{2}-[r(x)]^{2}dx

The Attempt at a Solution


x^6 - x^2 dx = x^7/7 - x^3/3 is where I get stuck.
 
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Since you're revolving it around the y axis, you would probably want to integrate the areas with respect to y. Once you do that and find your new limits of integration, there shouldn't be much of a problem getting the answer.

Edit: And don't forget about that Pi in the equation, when you integrated with respect to x you omitted it.
 
Last edited:
yes you want each slice perpendicular to the line you are rotating to. in your case, each slice will be (deltaY) high so you would integrate in terms of y, not x.

then it just becomes the integral of pi(Routside)^2-pi(Rinside)^2dy
 

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