Printable Worksheets
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Volume of Prisms and Cylinders
A water tank is a cylinder with radius 2 m and height 3 m. How many litres does it hold? (1 m³ = 1000 L)
Learning Intentions
Know
- Volume formula for prisms
- Volume formula for cylinders
- Composite solids
- Unit conversions
Understand
- Why volume scales with the cube of linear dimensions
- How to decompose complex shapes
Can Do
- Calculate volume of any prism
- Calculate volume of cylinders
- Find volume of composite solids
- Convert between cm³ and litres
Volume of Prisms
For any prism:
$V = A_{ ext{cross-section}} imes h$
This works because you are stacking identical cross-sections.
Rectangular prism: $V = lwh$
Triangular prism: $V = rac{1}{2}bh imes ext{length}$
Volume of Cylinders
For a cylinder:
$V = pi r^2 h$
The $pi r^2$ is the area of the circular base.
Example: Radius 5 cm, height 10 cm:
$V = pi imes 25 imes 10 = 250pi approx 785.4$ cm³
Composite Solids
A composite solid is made of two or more simple solids.
To find volume:
- Identify the component shapes
- Calculate each volume separately
- Add (or subtract) as appropriate
Example: A house-shaped solid = rectangular prism + triangular prism.
Check Understanding
A cylindrical tank has radius 1.5 m and height 2 m. Find its capacity in litres.
Volume Calculations
A rectangular prism is 8 cm × 5 cm × 4 cm. Find its volume.
$V = 8 imes 5 imes 4 = 160$ cm³
A cylinder has radius 3 cm and height 7 cm. Find its volume.
$V = pi imes 3^2 imes 7 = 63pi approx 197.9$ cm³
A composite solid: rectangular base 6×4×3 with a cylinder (r=2, h=3) on top. Find total volume.
Rectangular: $6 imes 4 imes 3 = 72$ cm³
Cylinder: $pi imes 4 imes 3 = 12pi approx 37.7$ cm³
Total: $72 + 37.7 = 109.7$ cm³
Common Misconceptions
Use diameter instead of radius in $pi r^2$. Always check: is the given measurement radius or diameter?
Forget to convert units. 1 m³ = 1,000,000 cm³ = 1000 L. Always check required units.
Add volumes when you should subtract. If a hole is drilled through a solid, subtract the hole's volume.
Practice — Volume Practice
Engineering and Design
Civil engineers calculate volumes for concrete pours, reservoir capacities, and earthworks. The Snowy Hydro scheme required precise volume calculations for tunnels and dams across the Australian Alps.
📓 Copy Into Your Books
▼Prism
- $V = A_{ ext{cross}} imes h$
- Units: cm³, m³
Cylinder
- $V = pi r^2 h$
- $SA = 2pi r^2 + 2pi r h$
Composite
- Break into parts
- Add or subtract volumes
- Watch units