Volume of Cylinders, Cones, and Spheres
A free Pre-Algebra lesson from the “Geometry Foundations” unit, with a worked example and practice problems including step-by-step solutions.
A cylinder's volume is the base area (pi r^2) times the height. A cone has 1/3 the volume of a cylinder with the same base and height. A sphere's volume is (4/3) pi r^3 — about two-thirds of the cylinder that snugly contains it (Archimedes).
What you'll learn
- Compute volume of a cylinder using V = pi * r^2 * h
- Compute volume of a cone using V = (1/3) * pi * r^2 * h
- Compute volume of a sphere using V = (4/3) * pi * r^3
Worked example
Problem. A cylinder has r = 3 and h = 10. Find V (pi = 3.14).
- V = pi * r^2 * h = 3.14 * 9 * 10.
- = 3.14 * 90 = 282.6.
Answer: 282.6
Practice problems
1. Cylinder r = 2, h = 10 (pi = 3.14).
Show solution
- Warm-up: First identify exactly what the question is asking: Cylinder r = 2, h = 10 (pi = 3.14).
- Use inverse operations to isolate the unknown, and keep both sides balanced at every step.
- V = 3.14 * 4 * 10.
- = 125.6.
- Check the result by substituting or estimating: the response should match 125.6 and make sense in the original problem.
Answer: 125.6
2. Cylinder r = 5, h = 4 (pi = 3.14).
Show solution
- Warm-up: First identify exactly what the question is asking: Cylinder r = 5, h = 4 (pi = 3.14).
- Use inverse operations to isolate the unknown, and keep both sides balanced at every step.
- V = 3.14 * 25 * 4.
- = 314.
- Check the result by substituting or estimating: the response should match 314 and make sense in the original problem.
Answer: 314
3. Cone r = 3, h = 10 (pi = 3.14).
Show solution
- Warm-up: First identify exactly what the question is asking: Cone r = 3, h = 10 (pi = 3.14).
- Use inverse operations to isolate the unknown, and keep both sides balanced at every step.
- V = (1/3) * 3.14 * 9 * 10.
- = (1/3) * 282.6 = 94.2.
- Check the result by substituting or estimating: the response should match 94.2 and make sense in the original problem.
Answer: 94.2
4. Cone r = 6, h = 5 (pi = 3.14).
Show solution
- Core Practice: First identify exactly what the question is asking: Cone r = 6, h = 5 (pi = 3.14).
- Use inverse operations to isolate the unknown, and keep both sides balanced at every step.
- V = (1/3) * 3.14 * 36 * 5.
- = (1/3) * 565.2 = 188.4.
- Check the result by substituting or estimating: the response should match 188.4 and make sense in the original problem.
Answer: 188.4
5. Sphere r = 3 (pi = 3.14).
Show solution
- Core Practice: First identify exactly what the question is asking: Sphere r = 3 (pi = 3.14).
- Use inverse operations to isolate the unknown, and keep both sides balanced at every step.
- V = (4/3) * 3.14 * 27.
- = 4 * 28.26 = 113.04.
- Check the result by substituting or estimating: the response should match 113.04 and make sense in the original problem.
Answer: 113.04
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