Video:How to Find the Volume and Surface Area of a Spherewith Eric Stone
Our expert shows you how to calculate the volume and surface area of a sphere. See how to easily find the volume and surface area of a sphere.See Transcript
Transcript:How to Find the Volume and Surface Area of a Sphere
Hi, I am Eric Stone from South Burlington High School in South Burlington, Vermont, here for About.com. Today, I am going to show you how to find the volume and surface area of a sphere.
Definition of a Sphere
A sphere is basically just a ball -- it has to be perfectly circular in all directions and it has a property which we call the radius. The radius is defined as the distance from the center of the sphere in the middle, all the way out to the edge. We are going to use 700,000 kilometers as the radius of the sun.
Finding the Volume of a Sphere
To find the volume it is pretty straightforward. The volume of a sphere is equal to four-thirds times pi times the radius cubed. So, if you want to find the volume of the sun, all you have to do is put it into this formula: four-thirds times pi times 700,000 kilometers cubed. You end up with a really big number: 1.4 x 10 to the eighteenth cubic kilometers. Wow!
Finding the Surface Area of a Sphere
The surface area is a really close formula to the volume. Let's stop and think for a second. The formula for volume has r-cubed -- three units of length, length, width and height. The surface area should only have two units, and indeed, it does. The area of a sphere is equal to four times pi times the radius squared.
So again, if we want to find the surface area of the sun, all I have to do is take the radius I was given and put it in for r. (Writes in 700,000 for r in the equation.) And I end up with yet another really big number: 6.2 x 10 to the twelfth kilometers, this time, squared.
And that's how you find the surface area and volume of a sphere.
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