Temperature and the Metric System

The English system is another recognized system of measurement. It is not universally accepted, and it consists of several units of measurements that are not functionally related to one another. This means the multiple of 10 cannot be used to convert one English unit to another. The following list provides the equivalent values of commonly used English measurements for length, weight, and volume. These values can be used when performing conversions from one English unit to another.

Length

• 12 inches = 1 foot (ft)
• 3 feet = 1 yard (yd)
• 5,280 feet =1 mile (mi)

Weight

• 16 ounces (oz) = 1 pound (lb)
• 1 ton = 2,000 pounds

Volume

• 8 ounces = 1 cup (c)
• 2 cups = 1 pint (pt)
• 2 pints = 1 quart (qt)
• 4 quarts = 1 gallon (gal)

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Did You Know?

The English system was created because people needed a way to describe measurements. Many of the measurements were based on the size of body parts and familiar objects. Eventually, this system was standardized into the system used today.

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Example

Metric Conversions

Recall that the metric system involves the use of prefixes and base units. The prefixes help a person identify how big or small the measured object is. What happens if one base unit needs to be converted to a different base unit? This is where the concept of using multiples of 10 is important.

When making metric conversions, it is helpful to create a metric staircase, as shown below.

Look at each step on the staircase. It represents a ten-fold change in the metric system. In other words, each step indicates that the decimal place of the measured unit value moves to the left or to the right. Moving to the right (or down the staircase) requires multiplication, which involves using multiples of 10 to convert the larger unit to a smaller unit. When moving to the left (or up the staircase), a smaller unit is converted to a larger unit by dividing using a multiple of 10.

Keep In Mind

It is helpful to use the following mnemonic to remember the order of the metric prefixes to ensure proper movement of the decimal between units from largest to smallest.

King Henry Doesn’t [Usually] Drink Chocolate Milk

Where king means “kilo,” Henry means “hecto,” doesn’t means “deca,” usually represents the base unit, drink means “deci,” chocolate means “centi,” and milk means “milli.”

Sometimes, it is necessary to do conversions between the metric and English systems. The following list provides commonly used English measurements and their respective (approximate) metric equivalent values.

Length

• 1 inch = 2.54 centimeters
• 1 yard = 0.91 meters

Weight

• 1 ounce = 28.3 grams
• 2.20 pounds = 1 kilogram

Volume

• 1.06 quart = 1 liter
• 3.79 liters = 1 gallon

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For Example

How many grams are in 2.52 kilograms?

The metric staircase indicates that kilogram is a larger unit than gram. Going down the staircase means the decimal must move to the right to give a value of 2,520 grams. If 2.52 is multiplied by the multiplying factor of 103, this will give the same value.

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Example

Temperature Systems

Three temperature scales are commonly used in science: Fahrenheit (F), Celsius (C), and Kelvin (K). Temperature measures the amount of kinetic energy that particles of matter have in a substance. Imagine that someone wants to boil a pot of water. Initially, the water molecules move very little. As the temperature rises to water’s boiling point, these molecules move faster, bouncing off each other and generating kinetic energy. Movement slows down as the temperature lowers to water’s freezing point.

The Fahrenheit temperature scale is part of the English system of measurement. It is not commonly used for scientific purposes like the Celsius (or centigrade) scale is. However, it is important to recognize and know how to use the conversion formulas between Celsius and Fahrenheit. The formulas are shown below:

\(F = \frac{9}{5}C + 32\)

\(C = \frac{5}{9}(F – 32)\)

The Fahrenheit scale is based on 32°F for the freezing point of water and 212°F for the boiling point of water. This corresponds to 0°C and 100°C, respectively, on the Celsius scale. The Celsius scale is part of the metric system, which means it is universally accepted when reporting temperature measurements. A thermometer is used to measure temperature. The following thermometers show common temperature values.

Kelvin is another temperature scale that is used. Its degrees are similar in size to degrees Celsius, but its zero is set to an absolute zero, or 0 K. This is the point where all molecular motion ends. On the Kelvin scale, the freezing point of water is 273.15 K. The boiling point is 373.15 K. The following equation is used to convert a Celsius reading to Kelvin:

K = °C + 273

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Be Careful

A degree sign is not used in the temperature designation for Kelvin. This symbol is only used with Fahrenheit and Celsius measurements.

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Example

Let’s Review

• The metric system is a universally accepted standard method that is used to determine the units of a given measurement.
• The English system is not universally accepted but provides a collection of measurements whose units are functionally unrelated.
• Meter (length), gram (weight), and liter (volume) are the most common types of SI base units.
• Metric prefixes are added to base units to describe the measurement of an object according to size.
• The metric staircase can be used for metric-metric conversions, and specific equivalent values are used for English-metric conversions.
• Three temperature scales, Celsius, Fahrenheit, and Kelvin, are used in science.
• Formulas are used to convert Celsius values to Fahrenheit or to Kelvin.