Chapter 8: Problem 43
Concern the region bounded by \(y=x^{2}\) \(y=1,\) and the \(y\) -axis, for \(x \geq 0 .\) Find the volume of the following solids. The solid whose base is the region and whose crosssections perpendicular to the \(x\) -axis are squares.
Short Answer
Expert verified
The volume of the solid is \( \frac{8}{15} \).
Step by step solution
01
Understanding the Problem
We are to find the volume of a solid whose base lies in the region bounded by the curve \( y = x^2 \), the line \( y = 1 \), and the \( y \)-axis, with \( x \geq 0 \). The cross-sections perpendicular to the \( x \)-axis are squares.
02
Identify the Boundaries
The region of interest is bounded by the parabola \( y = x^2 \), the line \( y = 1 \), and the \( y \)-axis. For \( y \) between 0 and 1, \( x \) ranges from 0 to \( \sqrt{y} \).
03
Determine the Cross-section
For each \( x \), the square cross-section perpendicular to the \( x \)-axis has a side length equal to the length running from \( y = x^2 \) to \( y = 1 \). This length is \( 1 - x^2 \).
04
Calculate the Volume
The area of each square cross-section is \( (1 - x^2)^2 \). To find the volume, integrate this area with respect to \( x \) from \( x = 0 \) to \( x = 1 \) (where \( x \) ranges between \( y = x^2 = 0 \) and \( y = 1 \)). The volume \( V \) is given by \( V = \int_{0}^{1} (1 - x^2)^2 \; dx \).
05
Evaluate the Integral
Expand \( (1 - x^2)^2 = 1 - 2x^2 + x^4 \) and integrate term-by-term:\[\int_{0}^{1} (1 - 2x^2 + x^4) \; dx = \left[ x - \frac{2}{3}x^3 + \frac{1}{5}x^5 \right]_{0}^{1} = \left[ 1 - \frac{2}{3} + \frac{1}{5} \right] = \frac{8}{15}.\]
06
Conclusion
The volume of the solid is \( \frac{8}{15} \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Integration
Integration is a mathematical tool that allows us to calculate the accumulation of quantities, such as areas, volumes, or any continuous element distributed over a range. In the case of volumes of solids, integration helps in summing up infinitely small cross-sectional areas along a specified boundary.
In this problem, integration is used to calculate the volume of a solid with square cross-sections. The function that defines our cross-sections is based on the curve formulas within the given region. By integrating the area function of these cross-sections over the designated interval (here from 0 to 1), we find the total volume of the solid.
In this problem, integration is used to calculate the volume of a solid with square cross-sections. The function that defines our cross-sections is based on the curve formulas within the given region. By integrating the area function of these cross-sections over the designated interval (here from 0 to 1), we find the total volume of the solid.
- First, express the area of each cross-section as a function of a variable (usually x).
- Integrate this area over the boundaries that define the entire solid.
- Calculation of this integral gives the volume of the solid.
Square Cross-sections
Square cross-sections mean that when we slice through the solid perpendicularly, each slice resembles a square. Each slice has equal side lengths, defined by the region’s constraints or boundaries
For our problem, the square cross-sections of the solid lie perpendicular to the x-axis. To determine the side length of these squares, one must consider the range defined by the equations. The side length is given by the vertical distance from the curve \( y = x^2 \) to the horizontal line \( y = 1 \).
For our problem, the square cross-sections of the solid lie perpendicular to the x-axis. To determine the side length of these squares, one must consider the range defined by the equations. The side length is given by the vertical distance from the curve \( y = x^2 \) to the horizontal line \( y = 1 \).
- The side length of each square, perpendicular to the x-axis, is \( 1 - x^2 \).
- The area of each cross-section, being a square, is \((1 - x^2)^2\).
Boundaries of Regions
Boundaries of a region define the limits within which the solid exists. These are essential to understand the extent of integration and the shape of the cross-sections.
Here, the solid is bounded by:
Here, the solid is bounded by:
- The parabola \( y = x^2 \).
- The horizontal line \( y = 1 \).
- The y-axis, which implies \( x \geq 0 \).