An Introduction to All Things Quantitative Measurements An Introduction to All Things Quantitative

Objectives After this presentation, you should be able to: Describe the need for measuring things. Define quantitative in your own words. Name and describe five properties that can be measured. Name the two systems of measurement in use and how they differ.

Why Measure? Measurements are among the earliest tools created by human beings. They were created to accomplish many tasks including: The construction of dwellings and monuments The fashioning of clothing The bartering of food or raw materials

What Can be Measured? There are many physical properties that can be measured in the world around us. Any property that can be measured and assigned a numerical value is said to be a quantitative (think quantity) property. Examples of quantitative properties include length, weight, brightness, heat, loudness, volume, as well as many more.

More Quantitative Properties Time Mass Amount Electrical current Area Speed Velocity Density

Systems of Measurement In use today, there are two major systems of measurement, the Imperial units (upon which our system of measurements are largely based) and the metric system. We, in the United States are probably most familiar with the Imperial system, however in the majority of the rest of the world, the metric system is the dominant system of measurements.

History of Measurement Length A cubit is the length of the forearm from the tip of the elbow to the tip of the middle finger. The cubit was divided into two spans (the distance between the tip of the thumb to the tip of the pinky in an outstretched hand). It was also divided into six hands (the width of the hand) It was also dived into 24 digits (the width of the middle finger)

History of Measurement The inch, foot, and yard were derived from these units. The roman foot was divided into 12 unciae and 16 digits. The roman mile consisted of 5000 feet, or 1000 paces. Queen Elizabeth I changed the mile to what we know it as today, 5280ft.

The Need for Standardization During the development of measurements, the same unit came to measure slightly different amounts depending upon where in the world it was used, by whom it was being used, or who was the ruler of the country/empire at the time. This discontinuity led to trade disputes and made life difficult for merchants…a change was needed.

The Metric System (SI) The metric system (often abbreviated as the SI system due to its French roots) is the measurement system preferred by scientists around the world. It was created by the French and is used by all but three nations (Burma, Liberia, and The United States) as their official system of measurement.

The Metric System Perhaps the most significant advantage to the metric system is the fact that it address the seemingly arbitrary relationship between different units for measuring the same property within the imperial system. Examples: Why are there 12 inches in a foot, but three feet in a yard? Why are their 2 pints in a quart, but 4 quarts in a gallon?

The Metric System Because it is based on powers of 10, the metric system makes it easy to go from small units to large units within the base (length, mass, volume…etc). For example, there are 10 millimeter in 1 centimeter, there are 1000 meters in 1 kilometer, there are 10 grams in one decagram.

The Metric System Another important characteristic of the metric system is the interconnectedness of the base units of mass, length, and volume and time. If we construct a box whose sides are all 1cm x 1cm, it would fit exactly 1 milliliter of water whose mass would be exactly 1 gram. If we construct a pendulum whose length is 1 meter, its period (the time it takes to complete a swing) is 1 second.

Wrap up Why measure? What is a quantitative property? What are five properties that can be measured? What are the two dominant systems of measurement in use today and how do they differ?