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Measurement - Volume of Cubes and Cuboids (Rectangular Prisms)

Grade 6IB

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

Volume represents the total amount of three-dimensional space an object occupies. To visualize this, imagine filling a hollow container with unit cubes (cubes with a side length of 11 unit); the volume is the total count of those cubes required to fill the container completely.

A rectangular prism, also known as a cuboid, is a 3D shape with six rectangular faces. It is defined by three dimensions: length (ll), width (ww), and height (hh). Visually, the length and width form the flat rectangular base, while the height determines how many layers of that base are stacked vertically.

A cube is a specific type of rectangular prism where all three dimensions (length, width, and height) are equal. Because every face is an identical square, we refer to the dimension simply as the side or edge length (ss).

Units of volume are always expressed in 'cubic' units, such as mm3mm^3, cm3cm^3, or m3m^3. This '3' exponent indicates that the measurement accounts for three dimensions (length, width, and height) being multiplied together.

The volume of a prism can be understood by calculating the 'Base Area' first. If you calculate the area of the bottom face (l×wl \times w), you are finding out how many unit squares cover the floor of the prism. Multiplying this area by the height (hh) tells you how many of those layers fill the entire height.

Capacity is the volume of fluid a container can hold. In the metric system, there is a direct relationship between solid volume and liquid capacity: 1cm31 cm^3 is equal to 1ml1 ml, and 1000cm31000 cm^3 is equal to 1L1 L.

To find a missing dimension when the volume is known, you can rearrange the formula. For instance, if you know the volume and the base area, you can find the height by dividing the volume by the base area: h=Vl×wh = \frac{V}{l \times w}.

📐Formulae

V=l×w×hV = l \times w \times h

V=s3=s×s×sV = s^3 = s \times s \times s

BaseArea=l×wBase Area = l \times w

V=BaseArea×heightV = Base Area \times height

h=Vl×wh = \frac{V}{l \times w}

💡Examples

Problem 1:

A rectangular storage box has a length of 12cm12 cm, a width of 7cm7 cm, and a height of 5cm5 cm. Calculate its total volume.

Solution:

V=l×w×hV = l \times w \times h V=12cm×7cm×5cmV = 12 cm \times 7 cm \times 5 cm V=84cm2×5cmV = 84 cm^2 \times 5 cm V=420cm3V = 420 cm^3

Explanation:

To find the volume of the cuboid, identify the three dimensions and multiply them together. First, multiply the length (1212) by the width (77) to find the area of the base (84cm284 cm^2), then multiply that result by the height (55) to find the total space occupied.

Problem 2:

The volume of a rectangular prism is 180m3180 m^3. If the length is 9m9 m and the width is 4m4 m, find the height of the prism.

Solution:

V=l×w×hV = l \times w \times h 180=9×4×h180 = 9 \times 4 \times h 180=36×h180 = 36 \times h h=18036h = \frac{180}{36} h=5mh = 5 m

Explanation:

When the volume and two dimensions are provided, first calculate the area of the base by multiplying length and width (9×4=369 \times 4 = 36). Then, divide the total volume (180180) by the base area to isolate and solve for the missing height (hh).