Math Problem Statement

Tentukan volume nya

Tentukan volume benda yang alasnya adalah daerah yang dibatasi oleh grafik-grafik y = √x dan y = x^2, dengan penampang tegak lurus sumbu x berbentuk setengah lingkaran. Tentukan juga volume irisan dua buah seperempat silinder berjari-jari satu.

Solution

The problem consists of two parts. Let's tackle each part in detail.

Part 1

The volume of a solid whose base is bounded by y=xy = \sqrt{x} and y=x2y = x^2, with vertical cross-sections perpendicular to the xx-axis shaped as semicircles.

  1. Determine the bounds of xx: Find the intersection points of y=xy = \sqrt{x} and y=x2y = x^2 by setting x=x2\sqrt{x} = x^2. x=x4x4x=0x(x31)=0x = x^4 \Rightarrow x^4 - x = 0 \Rightarrow x(x^3 - 1) = 0 This gives x=0x = 0 and x=1x = 1.

  2. Area of cross-section: For a given xx between 0 and 1, the length of the diameter of the semicircle is given by the distance between y=xy = \sqrt{x} and y=x2y = x^2: Diameter=xx2\text{Diameter} = \sqrt{x} - x^2 The radius rr of the semicircle is: r=xx22r = \frac{\sqrt{x} - x^2}{2} The area A(x)A(x) of the semicircular cross-section is: A(x)=12πr2=12π(xx22)2=π8(xx2)2A(x) = \frac{1}{2} \pi r^2 = \frac{1}{2} \pi \left(\frac{\sqrt{x} - x^2}{2}\right)^2 = \frac{\pi}{8} (\sqrt{x} - x^2)^2

  3. Volume of the solid: The volume VV is the integral of the cross-sectional area from x=0x = 0 to x=1x = 1: V=01A(x)dx=01π8(xx2)2dxV = \int_0^1 A(x) \, dx = \int_0^1 \frac{\pi}{8} (\sqrt{x} - x^2)^2 \, dx Expanding (xx2)2(\sqrt{x} - x^2)^2 gives: (xx2)2=x2x5/2+x4(\sqrt{x} - x^2)^2 = x - 2x^{5/2} + x^4 Thus, V=π801(x2x5/2+x4)dxV = \frac{\pi}{8} \int_0^1 (x - 2x^{5/2} + x^4) \, dx Integrate each term: V=π8[x222x7/27+x55]01V = \frac{\pi}{8} \left[ \frac{x^2}{2} - \frac{2x^{7/2}}{7} + \frac{x^5}{5} \right]_0^1 V=π8(1227+15)V = \frac{\pi}{8} \left( \frac{1}{2} - \frac{2}{7} + \frac{1}{5} \right) Simplify this to find the exact volume.

Part 2

The volume of the intersection of two quarter-cylinders of radius 1.

The shape created is a three-dimensional region where two quarter-cylinders intersect at right angles. This shape is known as the Steinmetz solid.

The volume VV of the intersection of two quarter-cylinders with radius r=1r = 1 can be found using the formula: V=2×(14πr2)2V = 2 \times \left( \frac{1}{4} \pi r^2 \right)^2 For r=1r = 1: V=2×(14π12)2V = 2 \times \left( \frac{1}{4} \pi \cdot 1^2 \right)^2 Compute this to find the volume.

Would you like a step-by-step calculation for each part or help with any specific step?

Questions to Explore Further

  1. How does the intersection of functions affect the volume in a solid of revolution?
  2. What are the applications of integrals in determining volumes of solids with different cross-sectional shapes?
  3. How can different shapes of cross-sections (e.g., squares, triangles) affect the overall volume calculation?
  4. What other methods exist for calculating the volume of the Steinmetz solid?
  5. How does symmetry simplify the computation of intersection volumes in geometry?

Tip

Using symmetry in volume integrals can greatly simplify calculations, especially with intersecting solids.

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Math Problem Analysis

Mathematical Concepts

Integral Calculus
Area of Cross-Section
Volume of Solids
Intersection of Solids

Formulas

Volume of solid with cross-sectional area V = ∫[a,b] A(x) dx
Area of a semicircle A = (1/2)πr^2
Intersection volume of two quarter-cylinders

Theorems

Definite Integral
Steinmetz Solid Volume

Suitable Grade Level

Undergraduate - Calculus Level