Python Program to Find Volume of Sphere

You can find the volume of a sphere in Python using the formula volume = (4/3) * 3.14159 * radius**3, where radius is the sphere's radius.

Examples

Inputradius = 1

OutputVolume of sphere with radius 1 is 4.188786666666666

Inputradius = 5

OutputVolume of sphere with radius 5 is 523.5983333333332

Inputradius = 0

OutputVolume of sphere with radius 0 is 0.0

How to Think About It

To find the volume of a sphere, you need to know its radius. The formula is four-thirds times pi times the radius cubed. You calculate the cube of the radius by multiplying the radius by itself three times, then multiply by pi and four-thirds to get the volume.

Algorithm

1

Get the radius value from the user or input.

2

Calculate the cube of the radius by multiplying radius by itself three times.

3

Multiply the cubed radius by pi (3.14159) and then by 4/3.

4

Store the result as the volume of the sphere.

5

Print or return the volume.

Code

python

radius = float(input("Enter the radius of the sphere: "))
volume = (4/3) * 3.14159 * radius**3
print(f"Volume of sphere with radius {radius} is {volume}")

Output

Enter the radius of the sphere: 5
Volume of sphere with radius 5.0 is 523.5983333333332

Dry Run

Let's trace the example where radius = 5 through the code

1

Input radius

User inputs radius = 5

2

Calculate radius cubed

5 ** 3 = 125

3

Calculate volume

(4/3) * 3.14159 * 125 = 523.5983333333332

4

Print result

Output: Volume of sphere with radius 5.0 is 523.5983333333332

Step	Operation	Value
1	Input radius	5
2	radius ** 3	125
3	(4/3) * pi * radius^3	523.5983333333332
4	Print output	Volume of sphere with radius 5.0 is 523.5983333333332

Why This Works

Step 1: Use the sphere volume formula

The formula volume = (4/3) * π * r³ calculates the space inside the sphere.

Step 2: Calculate radius cubed

Cubing the radius means multiplying it by itself three times: radius**3.

Step 3: Multiply by constants

Multiply the cubed radius by 4/3 and π to get the final volume.

Alternative Approaches

Using math.pi constant

python

import math
radius = float(input("Enter the radius of the sphere: "))
volume = (4/3) * math.pi * radius**3
print(f"Volume of sphere with radius {radius} is {volume}")

This uses Python's built-in math.pi for more accurate pi value.

Using a function to calculate volume

python

def sphere_volume(r):
    return (4/3) * 3.14159 * r**3
radius = float(input("Enter radius: "))
print(f"Volume: {sphere_volume(radius)}")

Encapsulates calculation in a function for reuse.

Complexity: O(1) time, O(1) space

Time Complexity

The calculation involves a fixed number of arithmetic operations, so it runs in constant time.

Space Complexity

Only a few variables are used, so the space needed is constant.

Which Approach is Fastest?

All approaches run in constant time; using math.pi is preferred for accuracy without affecting speed.

Approach	Time	Space	Best For
Using 3.14159 constant	O(1)	O(1)	Simple quick calculation
Using math.pi	O(1)	O(1)	More accurate pi value
Using function	O(1)	O(1)	Reusable code structure