Math Problem Statement

Use the general slicing method to find the volume of the following solid. The solid with a semicircular base of radius 5 whose cross sections perpendicular to the base and parallel to the diameter are squares Question content area bottom Part 1 The volume of the solid is    enter your response here cubic units. ​(Type an exact​ answer.)

Solution

To solve this problem using the general slicing method, we will follow the steps below:

Problem Restatement:

The solid has a semicircular base of radius 5. The cross-sections perpendicular to the base (parallel to the diameter) are squares. We are tasked with finding the volume of this solid.

Step 1: Set Up the Coordinate System

Let’s place the semicircle in the xy-plane. The equation for the upper half of a circle with radius 5, centered at the origin, is:

y=25x2y = \sqrt{25 - x^2}

This describes the top half of the semicircle with its base along the x-axis.

Step 2: Define the Cross-Sections

At any point x along the diameter, the length of the side of the square (the cross-section) is equal to the vertical distance from the x-axis to the semicircle. This distance is given by the equation for yy, i.e., the side of the square at each point is:

side length of the square=2y=225x2\text{side length of the square} = 2y = 2\sqrt{25 - x^2}

This is because the total length of the square’s side spans from the upper edge of the semicircle to the lower edge along the x-axis.

Step 3: Volume of the Slice

The area of the square cross-section is:

Area of square=(side length)2=(225x2)2=4(25x2)\text{Area of square} = (\text{side length})^2 = \left( 2\sqrt{25 - x^2} \right)^2 = 4(25 - x^2)

To find the volume of the solid, we integrate this area across the length of the base, from x=5x = -5 to x=5x = 5.

Step 4: Set Up the Integral

The volume VV of the solid is given by the integral of the area of the cross-section along the x-axis:

V=554(25x2)dxV = \int_{-5}^{5} 4(25 - x^2) \, dx

Step 5: Compute the Integral

First, expand the integrand:

V=455(25x2)dxV = 4 \int_{-5}^{5} (25 - x^2) \, dx

Now, break this into two simpler integrals:

V=4(5525dx55x2dx)V = 4 \left( \int_{-5}^{5} 25 \, dx - \int_{-5}^{5} x^2 \, dx \right)

  1. Integrating 2525:

5525dx=25x55=25(5)25(5)=250\int_{-5}^{5} 25 \, dx = 25x \Big|_{-5}^{5} = 25(5) - 25(-5) = 250

  1. Integrating x2x^2:

Since x2x^2 is an even function, the integral from 5-5 to 55 is twice the integral from 0 to 5:

55x2dx=205x2dx=2(x3305)=2(1253)=2503\int_{-5}^{5} x^2 \, dx = 2 \int_{0}^{5} x^2 \, dx = 2 \cdot \left( \frac{x^3}{3} \Big|_0^5 \right) = 2 \cdot \left( \frac{125}{3} \right) = \frac{250}{3}

Step 6: Final Calculation

Now, substitute these results back into the volume equation:

V=4(2502503)V = 4 \left( 250 - \frac{250}{3} \right)

Simplify:

V=4(75032503)=4(5003)=20003V = 4 \left( \frac{750}{3} - \frac{250}{3} \right) = 4 \left( \frac{500}{3} \right) = \frac{2000}{3}

Final Answer:

The volume of the solid is:

V=20003cubic unitsV = \frac{2000}{3} \, \text{cubic units}

Would you like to go over the steps again or have any questions? Here are some related topics for further exploration:

  1. How does the volume change if the cross-sections were circles instead of squares?
  2. Can we use the same method to calculate the volume of solids with triangular cross-sections?
  3. What happens to the volume if the radius of the semicircle changes to 10?
  4. How do you compute volumes of solids with irregular cross-sections?
  5. How would you approach the volume of a solid with elliptical cross-sections?

Tip: Always visualize the problem and sketch the region before setting up integrals, especially when dealing with solids with complex cross-sections.

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Math Problem Analysis

Mathematical Concepts

Calculus
Solid Geometry
Volume Calculation
Integration
General Slicing Method

Formulas

y = √(25 - x^2) (Equation for the upper half of the semicircle)
Area of square = (side length)^2 = 4(25 - x^2)
Volume = ∫ from -5 to 5 of 4(25 - x^2) dx

Theorems

General Slicing Method
Volume of Solids of Revolution

Suitable Grade Level

Grades 11-12