Volume of a Cylinder
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Volume of a Cylinder
The concept of volume, particularly in cylinders, is a practical and valuable skill in many real-life scenarios. For instance, knowing how to find the volume of a cylinder can help you determine how much water a bottle can hold or how many jelly beans can fit in a jar.
This knowledge is not just limited to classroom maths; it applies to everyday objects and situations, from sports equipment to household items. By learning about the volume of cylinders, you gain a useful tool that enhances your understanding of the world around you.
The volume of a cylinder is the amount of space inside the cylinder. It is calculated using the formula $V = \pi r^{2} h$, where $V$ is the volume, $r$ is the radius of the cylinder's base and $h$ is the height of the cylinder.
Understanding Volume of a Cylinder
The volume of a cylinder can be thought of as how much liquid or material it can hold. To calculate it, you need two measurements: the radius of the circular base and the height of the cylinder.
- The radius is the distance from the centre of the circular base to its edge.
- The height is the distance from the bottom to the top of the cylinder.
Volume of a Cylinder – Cubic Units
In calculating the volume of simple 3D shapes, the use of precise formulas is key, as is the necessity to accurately label the final solutions with their correct units.
Choosing the Correct Volume Units
Volume is expressed in cubic units because it represents three-dimensional space. Common units include cubic centimetres (cm³), cubic inches (in³) and cubic metres (m³). The unit used depends on the measurement units for radius and height.
Volume of a Cylinder – Step-by-Step
Here is the process to find the volume of a cylinder step by step.
| Step Number | Directions | Example |
|---|---|---|
| 1 | Identify the radius and height of the cylinder. | Radius $r = 4$ cm, Height $h = 10$ cm |
| 2 | Substitute the values into the formula $V = \pi r^{2} h$. | $V = \pi \times 4^2 \times 10$ |
| 3 | Calculate the volume, paying special attention to rounding rules. | $V = \pi \times 16 \times 10 = 160\pi$ cm³ approx. 502.6 cm³ |
| 4 | Write the final answer with the correct units. | Volume of the cylinder is 502.7 cm³ |
Let’s work through an example to understand how to calculate the volume of a cylinder.
Suppose a cylinder has a radius of 3 cm and a height of 10 cm. We want to find its volume.
For other shapes like Volume of a Sphere, we use different formulas to find their volume. But the way we do it is still step-by-step, just like with cylinders.
Finding the Volume ‘In Terms of $\pi$'
Leaving an answer 'in terms of $\pi$' means not using a numerical approximation for $\pi$ in the calculation. This form of answer is more precise, as it does not involve rounding off $\pi$ to a decimal. It is particularly useful in mathematical and scientific contexts where exact values are important.
Let’s look at the process of finding the volume of a cylinder ‘in terms of $\pi$'
Volume of a Cylinder – Real-World Problems
Cylinders are a common shape in our everyday lives, found in objects like soup cans, water towers and even in the structure of some buildings. Understanding how to calculate their volume helps us estimate the capacity of these everyday cylindrical objects.
Let’s take a look at some problems involving cylindrical objects we may encounter in the real world.
Volume of a Cylinder – Exercises
Using what you have learnt in this text, along with the formula for the Volume of a Cylinder, practice finding the volume!
Volume of a Cylinder – Summary
Key Points from this Text:
- The formula for calculating the volume of a cylinder is $V = \pi r^{2} h$.
- To find the volume, identify the radius and height of the cylinder.
- Substitute the values into the formula and use a calculator to compute, rounding to the nearest tenth or leaving in terms of $\pi$.
- This concept is widely used in real-world scenarios such as determining the capacity of containers.
Do you know what 3D shape has a volume that is exactly one-third of a cylinder with the same height and radius? A cone! Learn how to find the Volume of a Cone!
Volume of a Cylinder – Frequently Asked Questions
Transcript Volume of a Cylinder
A cylinder is a three-dimensional shape that we see in our everyday lives. They are made up of two circular bases, connected with a curved rectangular shape. The 'volume of a cylinder' measures how much space is inside the shape. The formula used is volume equals pi multiplied by the radius squared multiplied by the height. The radius is the distance from the middle of the circular base to the outside. The height is the length of the cylinder from one circular base to the other. Let's try out our first example! Find the volume of the cylinder and round the answer to the nearest tenth of a cubic inch. First, write the formula. The radius of this cylinder is six inches, so
Volume of a Cylinder exercise
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Understand the measurements in the formula for the volume of a cylinder.
HintsThe formula for the volume of a cylinder is $V=\pi r^2 h$.
Each of these variables refers to a measurement of the cylinder. Usually, these variables are also the first letter of the measurement on the figure.
The symbol $\pi$ is called pi and has an approximate value of $3.14...$.
A cylinder has two important measurements to find its volume.
$r$ = radius
$h$ = height
Solution$V$ = Volume
$\pi$ = pi
$r$ = radius
$h$ = height
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Which is the correct equation?
HintsThe formula for the volume of a cylinder is $V=\pi r^2 h$.
$r$ = radius
$h$ = height
Suppose there was a cylinder with a radius of $4$ cm and a height of $6$ cm.
The values for radius and height can be substituted into the formula.
$r=4$
$h=6$
$V=\pi r^2 h$
$V=\pi (\bf{4}^2)(\bf{6})$
SolutionThe $r$ is 7 cm and the $h$ is 10 cm. These values can replace the variables in the formula, $V=\pi r^2 h$.
$\bf{V=\pi (7^2)(10)}$
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Use a formula to find the volume of a cylinder.
HintsUse the formula for the volume of a cylinder, $V=\pi r^2 h$.
A calculator can help with calculating with $\pi$ more precisely, but if you do not have one available $3.14$ can be used.
SolutionThe volume of the cylinder is approximately 402 metres cubed.
$V \approx 402$ m$^3$
To find the volume, follow the steps:
$V=\pi r^2 h$
$r=4$
$h=8$
$V=\pi (4^2)(8)$
$V=402.1238597...$
$V \approx 402$ m$^3$
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Find the volume of a cylinder in terms of pi.
HintsIdentify the measurements, and substitute them into the formula for the volume of a cylinder.
Look at the circular base carefully to determine whether the radius or the diameter are provided.
Radius of a Cylinder: The distance from the centre to the edge of one of the cylinder's circular ends.
Diameter of a Cylinder: The distance across one of the cylinder's circular ends, from edge to edge through the centre, which is twice the radius.
In terms of pi means using the symbol $ \pi $ in your answer, which keeps it precise for circle-related maths, instead of using a decimal.
SolutionTo find the volume, in terms of pi, substitute the values for the radius and height into the formula.
Then, square the radius and multiply it with the height.
The $\pi$ will remain the symbol $\pi$ and this is the most precise measurement of the volume possible.
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What measurements would we use to find the volume of this cylinder?
HintsTo find the volume of a cylinder, the radius and height first need to be identified.
Radius of a Cylinder: The distance from the centre of one of the cylinder's circular bases to its edge.
Height of a Cylinder: The distance between the two circular bases of the cylinder, measuring how tall it is.
After determining the measurements, these values can be substituted in for the $r$ and the $h$ in the formula: $V=\pi r^2 h$.
SolutionRadius = 4 cm
Height = 12 cm
Volume = $\bf{V=\pi (4^2)(12)}$
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Problem solve with the volume of a cylinder.
HintsUse the formula for the volume of a cylinder.
$r$ = radius
$h$ = height
It may help you to use a piece of paper and a pencil to solve this problem. In addition, a calculator will help find the approximate volume.
Rounding to the nearest cubic inch means rounding to the nearest whole number.
Solution$V=\pi r^2 h$
$d=6$
$r=3$
$h=10$
$V=\pi (3^2)(10)$
$V \approx 283$ cubic inches
Since the liquid Kai needs to store is 250 cubic inches, this amount will fit in a cylindrical container with a volume of approximately 283 cubic inches.
