Our radius of a sphere calculator is a perfect tool that can estimate every parameter of a sphere from just one another quantity. However, it is mainly designed to support the computation of sphere radius. Try this calculator now by entering one of the chosen parameters into the appropriate field or read on and learn how to find the radius of a sphere. In the following text, we have also presented four different radii of a sphere formulas. A sphere is a perfectly round geometrical object in 3D space. The points on its surface are equally distant from the center of a sphere. It is an analog to a circle in 2D space. The radius of a sphere calculator uses five variables that can completely describe any sphere:
A sphere is a special object because it has the lowest surface to volume ratio among all other closed surfaces with a given volume. Also, here we can find the analogy to the circle, which encloses the largest area with a given perimeter. This radius of a sphere calculator, as the name suggests, contains information dedicated mostly to the radius of a sphere. For more general information about spheres, check out our sphere calc! There is an object called hemisphere that you can construct from any sphere you want. You just need to divide a sphere into two equal parts. The description of a hemisphere is a little bit more complicated compared to the full sphere, but it is possible. If you want to learn more about that kind of object, check out area of a hemisphere calculator and volume of a hemisphere calculator.
How to find the radius of a sphere? Actually, there are many various answers to that question because it depends on what we know about a specific sphere. Below, we have provided an exhaustive set of radius of a sphere formulas:
Our radius of a sphere calculator uses all of the above equations simultaneously, so you need to enter just one chosen quantity. Moreover, you can freely change the units (SI and imperial units). Check out our length conversion to learn how to switch between different units of length! Derivation of the above radius of sphere formulas is, in fact, straightforward. You need to make some algebraic transformations using the following basic equations:
This question seems very easy at first. You only have to find the center of the sphere and measure the distance to any point on its surface. However, how can you find this center in real, physical sphere, especially when it's closed? Let's look on a two of our suggestions:
We didn't write about finding the surface area of the sphere first because it is much harder to do it (compared to finding the radius). It is worth mentioning that spheres can often simplify various problems in physics. That's why they are widely used in this field, e.g., to model spherical capacitors or atoms of a gas.
To calculate the radius of a sphere given the volume:
1.99 cm. To calculate the radius r of a sphere given the surface area (A), rearrange the formula: r = √[A / (4 * π)] Notice how the area of a sphere is exactly four times the area of the circle with the same radius!
If you approximate the Earth as an ideal sphere (it is, in fact, a geoid) and you know the volume, you can calculate its radius. The numbers will be big, though! r = ³√[3 * V / (4 * π)] = 6371 km. This is not a bad approximate, as the radius of Earth actually ranges from 6357-6378 km!
Measuring the radius of a sphere is not that easy. You can wrap a string around it and hope you got the great circle, or you can be a bit more creative:
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