Math Problem Statement

Compute the volume of the solid whose base is the region in the first quadrant bounded by y = x^6, y = 1, and the y-axis, and whose cross sections perpendicular to the y-axis are equilateral triangles.

Solution

To compute the volume of the solid whose base is the region in the first quadrant bounded by y=x6y = x^6, y=1y = 1, and the yy-axis, and whose cross-sections perpendicular to the yy-axis are equilateral triangles, we can break the problem down step by step.

Step-by-Step Solution:

  1. Cross-sectional Area: The cross-sections are equilateral triangles. The side length of each equilateral triangle depends on the value of xx for each yy-value.

    Since the equation y=x6y = x^6 defines the relationship between xx and yy, we can solve for xx as a function of yy: x=y1/6x = y^{1/6} This gives us the base of the equilateral triangle for each value of yy.

  2. Area of an Equilateral Triangle: The area AA of an equilateral triangle with side length ss is given by: A=34s2A = \frac{\sqrt{3}}{4} s^2 Here, the side length of the triangle is 2x=2y1/62x = 2y^{1/6}. So, the area becomes: A(y)=34(2y1/6)2=344y1/3=3y1/3A(y) = \frac{\sqrt{3}}{4} (2y^{1/6})^2 = \frac{\sqrt{3}}{4} \cdot 4y^{1/3} = \sqrt{3} y^{1/3}

  3. Volume Integral: The volume VV of the solid is obtained by integrating the cross-sectional area A(y)A(y) from y=0y = 0 to y=1y = 1: V=01A(y)dy=013y1/3dyV = \int_0^1 A(y) \, dy = \int_0^1 \sqrt{3} y^{1/3} \, dy

  4. Evaluate the Integral: We can now compute the integral: V=301y1/3dyV = \sqrt{3} \int_0^1 y^{1/3} \, dy The antiderivative of y1/3y^{1/3} is: 34y4/3\frac{3}{4} y^{4/3} So the integral becomes: V=3[34y4/3]01=334(14/304/3)V = \sqrt{3} \left[ \frac{3}{4} y^{4/3} \right]_0^1 = \sqrt{3} \cdot \frac{3}{4} \cdot \left( 1^{4/3} - 0^{4/3} \right) V=334=334V = \sqrt{3} \cdot \frac{3}{4} = \frac{3\sqrt{3}}{4}

Final Answer:

V=334V = \frac{3\sqrt{3}}{4}

Let me know if you need any clarifications or further details!

Related Questions:

  1. How do you calculate the volume of solids with different cross-sectional shapes?
  2. What happens if the cross-sectional shape is not equilateral but isosceles?
  3. Can you compute the volume of the solid if the base is different, say a semicircle?
  4. How does changing the power in the equation y=xny = x^n affect the volume?
  5. How do you approach volumes when the cross-section is a function of two variables?

Tip:

For volumes of solids of known cross-sections, always identify the relationship between the base dimensions and the cross-sectional area formula. This makes setting up the integral easier!

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Math Problem Analysis

Mathematical Concepts

Volume of Solids
Cross-sectional Area
Integral Calculus
Equilateral Triangles

Formulas

Area of equilateral triangle: A = (sqrt(3)/4) * s^2
Volume of solid using integral: V = ∫ A(y) dy
Relation between x and y: x = y^(1/6)

Theorems

Fundamental Theorem of Calculus

Suitable Grade Level

Undergraduate Calculus