Volume of Cylinders

Lesson 18

Find the area of each circle. Use 3.14 for .

1.

2.

3. What will have more area, a square with sides that are 10 units or a circle with a diameter of 10 units?

Target: Calculate the volume of cylinders.

The volume of a cylinder is equal to the product of the area of the base (B) and the height (h).

V = Bh

V = πr2h

Find the volume of the cylinder.Use 3.14 for π.

Write the formula. V = πr2h Substitute known values. V ≈ (3.14)(8)2(5) Find the value of the power. V ≈ (3.14)(64)(5) Multiply. V ≈ 1004.8

The volume of the cylinder is about 1,004.8 cubic meters.

A silo is filled with corn to the top of the cylindrical part.The cylindrical part of the silo is 90 feet tall and has a diameterof 15 feet. About how many cubic feet of corn does the silohold?

Find the length of the radius. 15 ÷ 2 = 7.5 Write the formula. A = πr2h Substitute known values. A ≈ (3.14)(7.5)2(90) Find the value of the power. A ≈ (3.14)(56.25)(90) Multiply. A ≈ 15,896.25 Round the answer. A ≈ 15,896 The silo holds about 15,896 cubic feet of corn.

The volume of cylindrical water cooler is 1695.6 cubic inches.The cooler has a radius of 6 inches. Find the height of the cooler. Use 3.14 for π.

Write the needed volume formula. A = πr2h Substitute known values. (1695.6) ≈ (3.14)(6)2h Find the value of the power. 1695.6 ≈ (3.14)(36)h Multiply. 1695.6 ≈ 113.04h Divide. 113.04 113.04

15 ≈ h The height of the water cooler is about 15 inches.

1. Find the volume of the cylinder. Use 3.14 for .

2. A circular swimming pool can hold 7850 cubic feet of water. The diameter of the pool is 50 feet. Find the height of the swimming pool. Use 3.14 for .

You are helping out in a 2nd grade math class. Thestudents know you are working on a unit about volume. One of the 2nd grade students asks you, “What is volume?” How would explain it to them?