Overview
This lecture introduces the concept of measurement, emphasizes the importance of standardized units, and explains the basics of the Metric System, including units of length and mass and their conversion.
Measurement Basics
- Measurement quantifies physical properties like size, weight, and volume using numbers.
- Relative descriptions (e.g., "tall", "heavy") lack precision compared to numerical measurements.
- Units of measurement are agreed-upon reference quantities used to express measurements.
- Standardizing units ensures consistency and comparability between different people and situations.
- Official agencies (e.g., Bureau of Weights and Measures) define and maintain these standards.
The Metric System (S.I. Units)
- The Metric System is the most widely used system of units globally, also called "International System of Units" (S.I.).
- Units in the Metric System are based on powers of 10, simplifying conversion and calculation.
- Each base unit can be modified by prefixes to indicate multiples or fractions by powers of 10.
Metric Units of Length
- The base unit for length is the meter (m).
- Larger units: dekameter (10 m), hectometer (100 m), kilometer (1,000 m).
- Smaller units: decimeter (0.1 m), centimeter (0.01 m), millimeter (0.001 m).
- Prefixes and their abbreviations make writing and converting units convenient.
- Converting between metric units involves multiplying or dividing by 10 (shifting the decimal).
Metric Units of Mass
- The base unit for mass is the gram (g), but the kilogram (kg) is often used.
- Larger units: dekagram (10 g), hectogram (100 g), kilogram (1,000 g).
- Smaller units: decigram (0.1 g), centigram (0.01 g), milligram (0.001 g).
- Conversion between units uses powers of 10, just like with length units.
- Most frequently used units: milligram, gram, kilogram.
Metric Units of Time
- The base S.I. unit of time is the second (s).
- Units larger than a second (minute, hour, day) are not metric-based.
- Sub-second units (millisecond, nanosecond) use metric prefixes.
Key Terms & Definitions
- Measurement — expressing a property (like length or mass) as a number.
- Unit of Measurement — a standard quantity used as a reference in measurement.
- Metric System (S.I. Units) — a decimal-based system of measurement using standardized units and prefixes.
- Prefix — a syllable added to a unit name indicating multiples or fractions by powers of 10.
Action Items / Next Steps
- Practice simple exercises converting between metric units of length and mass.
- Review and memorize the common metric prefixes and abbreviations.