Choosing Appropriate Units of Measure

In the physical world around us, we come across the quantities such as time, distance, mass, area, volume, and so on. In a mathematics course, we are more interested in the units of measurements, which are used to describe the magnitude of each of these quantities.

Some units of measurement are given below:

Time	Distance (Metric)	Distance (Customary)	Mass (Metric)	Weight (Customary)
Second	Millimeter	Inch	Milligram	Ounce
Minute	Centimeter	Foot	Gram	Pound
Hour	Meter	Yard	Kilogram	Ton
Day	Kilometer	Mile	Metric Ton
Month
Year
Century

While describing various physical quantities, it is best to use appropriate units of measure. Using other units of measure to describe a quantity gives either very small or very large number value. It becomes difficult to estimate the magnitude of the quantity, if inappropriate units are used.

Quantity	Appropriate unit of measure
Distance between two cities	Miles or kilometers
Height of a person	Feet and inches, or centimeters
Weight of a person	Pounds or kilograms
Height of a high-rise building	Meters or feet
Height of a mountain peak	Meters or feet
Depth of a ocean	Meters or feet
Area of a football field	Feet ^$2$ or meters ^$2$
Capacity of milk bottle	Liters
Size of a Paper	Inches or centimeters
Time taken to complete $100$ meter race	Seconds
Time taken to travel between two cities by car	Hours

Example:

What is the appropriate unit of measure used to describe the width of a computer monitor?

Answer:

Imagine yourself measuring the width of a computer monitor with a tape measure . What is the approximate value you could get?

The width of computer monitor is usually between $10$ inches and $20$ inches.

We know that $1 inch =$ $2.54$ centimeters. So, when these values are converted to centimeters, it is about $25$ and $50$ .

Can you measure the width of the same computer in feet or meters?

Very small numbers (less than $1$ ) are needed to express the width of the computer in feet or meters. So, it is not possible to accurately measure the width of computer monitor in feet or meters.

Therefore, the appropriate unit of measure to describe the width of a computer monitor is inches or centimeters .

Choosing Appropriate Units of Measure

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