Chapter 9: Problem 282
Find a the volume and b the surface area of the sphere with the given radius. Round answers to the nearest hundredth. 2.1 yards
Short Answer
Expert verified
Volume: 38.84 cubic yards; Surface Area: 55.42 square yards.
Step by step solution
01
Write the Formula for the Volume of a Sphere
The formula for the volume of a sphere is \( V = \frac{4}{3} \pi r^3 \), where \( r \) is the radius.
02
Plug in the Radius for Volume
Given the radius (r) is 2.1 yards, substitute this value into the formula: \( V = \frac{4}{3} \pi (2.1)^3 \).
03
Calculate the Volume
First calculate \( (2.1)^3 \): \[ (2.1)^3 = 2.1 \times 2.1 \times 2.1 = 9.261 \] Then multiply by 4/3 and \( \pi \): \[ V = \frac{4}{3} \pi \times 9.261 \approx 38.84 \text{ cubic yards} \] (Rounded to the nearest hundredth).
04
Write the Formula for the Surface Area of a Sphere
The formula for the surface area of a sphere is \( A = 4 \pi r^2 \), where \( r \) is the radius.
05
Plug in the Radius for Surface Area
Given the radius (r) is 2.1 yards, substitute this value into the formula: \[ A = 4 \pi (2.1)^2 \].
06
Calculate the Surface Area
First calculate \( (2.1)^2 \): \[ (2.1)^2 = 2.1 \times 2.1 = 4.41 \] Then multiply by 4 and \( \pi \): \[ A = 4 \pi \times 4.41 \approx 55.42 \text{ square yards} \] (Rounded to the nearest hundredth).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Volume Calculation
Understanding how to calculate the volume of a sphere is essential in geometry. The formula used for this is \( V = \frac{4}{3} \pi r^3 \). This formula stems from integral calculus, but the main idea is to measure how much space a spherical object occupies.
Here's a step-by-step guide on calculating the volume:
Here's a step-by-step guide on calculating the volume:
- First, identify the radius (r) of the sphere. In our case, the radius is 2.1 yards.
- Next, use the volume formula: \( V = \frac{4}{3} \pi (2.1)^3 \).
- Simplify the expression by calculating the cube of the radius: \( (2.1)^3 = 9.261 \).
- Then, multiply by \( \frac{4}{3} \) and \( \pi \): \( \frac{4}{3} \pi \times 9.261 \).
- This gives approximately 38.84 cubic yards, as rounded to the nearest hundredth.
Surface Area Calculation
Next, let's talk about calculating the surface area of a sphere. The formula for surface area is \( A = 4 \pi r^2 \). This formula helps determine how much area covers the outer surface of the sphere.
Here are the steps to calculate it:
Here are the steps to calculate it:
- Start with the radius of the sphere, which is again 2.1 yards.
- Use the surface area formula: \( A = 4 \pi (2.1)^2 \).
- Calculate the square of the radius: \( (2.1)^2 = 4.41 \).
- Multiply the result by 4 and then by \( \pi \): \( 4 \pi \times 4.41 \).
- The final result is approximately 55.42 square yards, rounded to the nearest hundredth.
Sphere Geometry
To fully grasp the previous calculations, it's important to understand the basics of sphere geometry. A sphere is a perfectly round three-dimensional shape, where every point on its surface is equidistant from its center.
- The radius (r) is the distance from the center of the sphere to any point on its surface.
- The diameter is twice the radius, giving the longest distance across the sphere.
- Volume refers to the space inside the sphere.
- Surface area is the total area that the surface of the sphere occupies.