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Volume and Capacity - Mensuration | Class 8 Maths

Last Updated : 23 Jul, 2025
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Mensuration is the branch of mathematics that talks about the length, volume, and area of different geometrical objects. The shape may be in 2-D or 3-D. We find the volume of 3-D objects and the area of 2-D objects.

What is Volume?

Volume is the measurement of the total space occupied by a given solid. Volume is defined in 3-D because to have the volume the object must have three variables i.e. length, breadth or thickness or width, and height. 

The difference between the total amount of space left inside the hollow body and the space occupied by the body is the volume of the figure.

Now, let us take the example of a 3d shape called a cuboid, it is a solid figure bounded by six rectangles and thus has six rectangular faces. The dimensions of the cuboid are as follows: length l, breadth b, and height h.

Volume-and-Capacity-5-min

Volume of the cuboid is given as:

Volume = length * height * width

Volume is for both solid and hollow objects. E.g. Cube, Cuboid, Cone, Cylinder, etc. 

What is Capacity?

When the hollow object is filled with liquid or air and it takes the shape of that object or container. The total volume of the water and air which is filled inside the container is called the capacity of the container. 

Note: Capacity is calculated only for hollow object.

Example: Cone, Cylinder, Hollow hemisphere, etc.

Example: Find the volume and capacity of cylinder whose radius is 14 cm and height is 21cm.

Solution: We have given, r = 14cm, h = 21cm;

Volume of cylinder = πr*r*r*h.

V = 22/7 * 14 * 14 * 21

V = 12,936cm3.

and capacity is = 12,936/1000 litre     .......as (1000cm3= 1litre)

                          = 12.936 litre.

Note: The unit of capacity is litres(l) and millilitres(ml).

Use our calculator to convert litre to millilitre.

Mensuration of Some Enclosed Figures

Cube

Surface area of cube is defined as the area of every face of the cube. For e.g. as we know that every side of cube is equal. So area of one face is  length*length or width*width or height*height  out of these three we pick one according to question. 

So total surface area of cube is 6 * length * length. Because cube has six faces and each face has an area of length*length.

Now the volume of cube is its hollow portion and can be written as length * length * length or width * width * width or height * height * height. And its unit will be cubic.

Cube

Example: Find the width of the cube whose volume is 625cm3.

Solution: 

We know that volume of the cube is a * a * a =a3 where a  can be the length, width, height.

So, a3 = 125 then

a = 5cm ( 5 is cube root of 125)

So width is 5 cm.

Cuboid

Surface area of cuboid is defined as the surface area of cube but the difference here is all the sides are not equal and in cuboid length width height are different. So its surface area will be the area of each face and add all the areas which we will get total surface area. 

So total surface area of cuboid is length * width + width * height + height * length + length * width + width * height + height * length i.e. the addition of areas of every six face

So total surface area is 

2 * (length * width + width * height + height * length)

The volume of cuboid is the hollow portion inside the cuboid and it is 

Volume = length * width * height

Cuboid

Example: Find the height of cuboid volume is 625cm3 and its base area is 25 cm2.

Solution: 

Base area of cube means width * length this forms base in cube

As we know volume of cube is 

=> l * b * h = 625

=> h = 625 / b * l

=> h = 625 / 25

=> h = 25cm

So the height is 25 cm

Cylinder 

Here we are talking about right circular cylinder for e.g. round pillar, tube lights, water pipes, etc. Volume of cylinder is the hollow portion inside the cylinder.

Volume of Cylinder = 22/7 * r * r * h

Here, 

r = radius of cylinder and h = height of cylinder

Cylinder

Example: A rectangular sheet of paper having length 11cm and width 4cm  cm is being rolled to form a cylinder of height 4 cm. What is the volume of the cylinder?

Solution: 

Let the cylinder if radius = r and its height = h

Perimeter of  base of cylinder = 2 * pi * r = 11cm

                                                => 2 * 22/7 * r = 11cm

                                                => r = 7/4 cm

Volume = 22/7 * r* r * h

=> 22/7 * 7/4 * 7/4 * 4 

=> 38.5cm3

Hence, the volume of cylinder is 38.5cm3

Cone

Volume of cone is the hollow portion inside cone.

Volume = 1/3 * 22/7 * r * r * h

Here, 

h = height of cone

r = radius of cone

Cone

Formulas for Common Geometric Figures

1. Cube

(a) Surface Area:

Surface Area=6×(side 2)

(b) Volume:

Volume=side 3


2. Cuboid

(a) Surface Area :

Surface Area=2×(lw+lh+wh)

(b) Volume :

Volume=l×w×h


3. Cylinder

(a) Volume :

Volume=πr2h

Where 𝜋 ≈ 22/7 OR 𝜋 ≈ 3.14159


4. Cone

(a) Volume :

Volume= 1/3 πr2h


5. Sphere

(a) Surface Area :

Surface Area=4πr2

(b) Volume :

Volume= 3/4πr3

Step-by-Step Examples of Volume Calculation

Example 1: Cube

Problem: Find the width of a cube with a volume of 625 cm³.

Solution :

1. Volume Formula:

Volume=side3

2. Solve for side :

side=∛625 = 5cm.

3. Width = 5 cm.

Example 2: Cuboid

Problem: Find the height of a cuboid with a volume of 625 cm³ and a base area of 25 cm².

Solution:

1. Volume Formula:

Volume=Base Area X Height

2. Solve for height:

Height = Volume / Base = 625/ 25 = 25cm.

Example 3: Cylinder

Problem: A cylindrical container has a radius of 10 cm and a height of 7 cm. Find its volume.

Solution :

1. Volume Formula:

Volume=πr2h

2. Substitute values:

Volume = 22/7 X 102 X 7 = 4400cm3

Example 4: Cone

Problem: Find the volume of a cone with a radius of 9 cm and height 14 cm.

Solution :

1. Volume Formula:

Volume =1/3 πr2 h

2. Substitute values:

Volume = 1/3 X 22/7 X 92 X 14 =1188cm3

Conversion Between Different Units of Measurement

Volume to Capacity Conversion

1. Cubic Centimetres to Litres:

1 litre=1,000 cm3

To convert cubic centimetres to litres:

Capacity (litres) = Volume(cm3 ) / 1,000

2. Litres to Millilitres:

1 litre=1,000 millilitres

To convert litres to millilitres:

Capacity (millilitres) = Capacity (litres)×1,000

Example Conversions

1. Convert 12,936 cm³ to litres:

Capacity = 12,936 / 1,000 = 12.936 litres

2. Convert 1.5 litres to millilitres:

Capacity = 1.5 X 1,000 =1,500 millilitres

Summary

Mensuration is essential for determining the dimensions and capacity of various geometric figures. Understanding formulas for volume and surface area helps in solving real-world problems related to space and capacity. Mastery of unit conversions ensures accurate measurements and calculations.

Practice Problems: Volume and Capacity - Mensuration

Problem 1: Find the capacity of a cubic tank with dimensions 1 m × 1 m × 1 m.

Problem 2: A tank measures 2 m × 1 m × 2 m. Find the capacity of the tank.

Problem 3: Find the volume of a cylinder with a radius of 10 cm and height 7 cm.

Problem 4: Find the volume of a cone with radius 9 cm and height 14 cm.


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