英尺 <--> 米

(Video) Converting Units of Length: Feet to Meters

by MooMoo Math and Science

This Youtube video by MooMoo Math and Science covers conversion between units of measurement. While we can convert between feet and inches ($1$ foot equals $12$ inches), our focus here is converting between feet and meters. All three units are measurements of length and distance. We might use these to measure how wide your bedroom is, or how far the drive between two cities is.

$\large{\text{Summary}}$

We only need one number to convert between feet and meters. A meter is approximately equal to $3.28084 \text{ feet}$. The video includes three examples to explain this concept.

Let’s take a look at the first example.

Convert $12$ meters to feet.

Since we know that there are $3.28084 \text{ feet}$ in $1 \text{ meter}$, we can use this information to solve. $$\begin{align} 12 \text{ meters} \times \frac{3.28084 \text{ feet}}{1 \text{ meter}} &= 12 \cancel{\text{ meters}} \times \frac{3.28084 \text{ feet}}{1 \cancel{\text{ meter}}} \\ &= 12 \times 3.28084 \text{ feet} \\ &= 39.37008 \text{ feet} \\ \end{align}$$

The last example explains how to convert meters to inches. We start with the same units as in the first example, but finish with different units. There will be two separate conversions. First we convert from meters to feet. Then we convert from feet to inches. Remember, there are $12 \text{ inches}$ in $1 \text{ foot}$.

Convert $7 \text{ meters}$ to inches.
$$\begin{align} &7 \text{ meters} \times \frac{3.28084 \ \text{ feet}}{1 \text{ meter}} \times \frac{12 \text{ inches}}{1 \text{ foot}}\\ &= 7 \cancel{\text{ meters}} \times \frac{3.28084 \ \cancel{\text{ \ feet}}}{1 \cancel{\text{ meter}}} \times \frac{12 \text{ inches}}{1 \cancel{\text{ foot}}}\\ &= 7 \times 3.28084 \times 12 \text{ inches}\\ &= 22.96588 \times 12 \text{ inches}\\ &\approx 275.591 \text{ inches} \end{align}$$

Now we look at some conversion problems between feet and meters. We can also solve conversion problems between kilometers and miles. This is most useful for longer distances, such as the length driven on a road trip.

Solve using a conversion table. $$\begin{array}{c|c} 16\text{ feet}&1\text{ meter}\\ \hline &3.28084\text{ feet} \end{array}$$ $$\begin{array}{c|c} 16\cancel{\text{ feet}}&1\text{ meter}\\ \hline &3.28084\cancel{\text{ feet}} \end{array}= 4.8768\text{ feet}$$ $$\approx \boxed{5 \text{ feet}}$$

Solve using a conversion table. $$\begin{array}{c|c} 10\text{ meters}&3.28084\text{ feet}\\ \hline &1\text{ meter} \end{array}$$ $$\begin{array}{c|c} 10\cancel{\text{ meters}}&3.28084\text{ feet}\\ \hline &1\cancel{\text{ meter}} \end{array}= 32.8084\text{ meters}$$ $$\approx \boxed{33 \text{ meters}}$$

A $\text{meter}$ is $3.28084 \text{ feet}$

Meters and feet aren't from the same system of measurement, so conversion between them can be messy. Feet are among the list of Imperial Units. Meters are part of the International System of Units, and are the base unit of measurement for length. In other words, scientists start with meters and convert to other units of length.

For every meter, there are $3.28084$ feet. For every foot, there are $0.3048$ meters. Meters are sometimes abbreviated with an $\text{m}$, and feet with $\text{ft}$. $\textit{They are defined as being equal this way.}$ This ensures two people both measuring the same thing in feet get the same answer.

When we want to convert from m to ft, we can just multiply by $\frac{3.28084\text{ ft}}{1\text{ m}}$.

When we want to convert from ft to m, we instead multiply by $\frac{1\text{ m}}{3.28084\text{ ft}}$. No matter which direction we are doing, the units we want to get rid of will cancel out.

Example

So, if we want to convert $1$ meter to feet, do this: $$1\text{ m} \times \frac{3.28084\text{ ft}}{1\text{ m}} = \frac{1\text{ m} \times 3.28084\text{ ft}}{1\text{ m}} = \boxed{3.28084\text{ ft}}$$

$$5280\text{ ft} \times \frac{1\text{ m}}{3.28084\text{ ft}} = \frac{5280\text{ ft} \times 1\text{ m}}{3.28084\text{ ft}} = \boxed{1609.344\text{ m}}$$

So, $5{,}280 \text{ feet}$ is equal to $1{,}609.344 \text{ meters}$! (There are also $5{,}280 \text{ feet}$ in a $\text{mile}$, so a $\text{mile}$ is equal to $1{,}609.344 \text{ meters}$, too).

Use the knowledge that $1 \text{ meter}$ equals $3.28 \text{ feet}$ to convert $\text{feet}$ to $\text{meters}$ and vice versa.

We multiply when converting from bigger to smaller units, divide when converting from smaller to bigger units.

For example:

Feet is a smaller unit than a meter is, since $1 \text{ foot}$ is shorter than $1 \text{ meter}$. So, when converting from feet to meters, we divide. $$1\text{ ft} =\frac{1}{3.28}\text{ m}=0.305\text{ m}$$