Measurement in Science

Customary Units vs. Metric Units DISTANCE Inches, Feet, Yards, Miles Meters LIQUIDS Cups,Pints, Quarts, Gallons Liters WEIGHT/ MASS Ounces, Pounds, Tons Grams TEMPERATURE ° Fahrenheit ° Celsius

Why are measurement standards important? What is a standard? It is an exact quantity that people agree to use for comparison. Why are measurement standards important? A meter in the U.S. is the same as a meter in France.

SI Units are... International Standards Abbreviated SI from the French Le Systeme Internationale d’Unites or the Common Name of the Metric System

Can you think about any situations that we use the Metric System in our everyday life – either home or at school? Name at least 3 examples: 1. 2. 3. Come on brain!!

Pros & Cons of Metric System Why should we use this system? Pro’s Easy: based on the use of ten Conversions are easier - Just move decimal point Used all over the world – not just USA Con’s History of conflict all over the world People don’t want to change Replacement cost of machinery too high

What do all those prefixes mean? International Standard Units (SI)

Putting It All Together prefix symbol unit centi- c m meter (0.01) hundredth of a meter milli- L m liter (.001) thousandth of a liter kilo- k g gram (1000) thousand grams

King Henry dances merrily down center main. How can I remember the order? From LARGEST to smallest the easiest way to remember the prefixes is in a sentence…….. King Henry dances merrily down center main. Or.. King Henry doesn’t milk dairy cows on Mondays. Kilo- Hecto- Deka- BASE deci- centi- milli- Meter, Liter, Grams

Metric Conversions Step 1: Locate the DECIMAL POINT in the number that you need to convert. 27.025 g = _________ cg Decimal Point Step 2: Mark the starting point (where the decimal point is in the original number) on the guide. Kilo- Hecto- Deka- BASE deci- centi- milli- .

This is the direction the Step 3: Mark the ending point (where the decimal point is in the final number) on the guide with an X. Kilo- Hecto- Deka- BASE deci- centi- milli- . X This is the direction the DECIMAL will move. 27.025 g = _________ cg

. 2702.5 27.025 g = _________ cg 27.025 g = _________ cg Step 4: Move the decimal point (.) in the direction of the X. Stop moving the decimal when you reach the X. That’s how many places you need to move the decimal point in the original number. . Kilo- Hecto- Deka- BASE deci- centi- milli- X 1 2 27.025 g = _________ cg 27.025 g = _________ cg 2702.5

SI Units for Measurement Used in Science Length / Distance Metric ruler: Measured in meters (m) Volume Regular Shape – Length X Width X Height Measured in cm3 Example: box, land, table tops Metric ruler: Irregular Shape – Displacement Method Final Reading – Initial Reading = Volume Measured in milliliters (mL) Example: Liquids, rocks, marbles Graduated cylinder:

Continued - SI Units for Measurement Used in Science Mass Balance: Measured in grams (g) Temperature Thermometer: Measured in degrees Celsius (OC) Time Clock: Measured in seconds (s)

Density …the amount of mass in a given volume Formula to calculate Density: Units are expressed as: - g/mL – density of a liquid - g/cm3 – density of a solid Mass Volume Density = D M V

Using a Ruler When measuring an object with a ruler, never start at the “0” mark. Rulers are less accurate due to wear and tear at the ends. Begin at the 2, 4, 5 or 6 cm mark in order to get the most accurate mark. 5 6 What is the length of the red line? 6.2 cm or 1.2 cm The red line would be 1.2 cm because the “5” is the starting point. 6.2 – 5 cm = 1.2 cm

Reading the Meniscus When measuring liquid volume in a graduated cylinder, a meniscus often forms where the liquid ends. graduated cylinders In order to read this liquid volume, you must be at “eye-level” to the level of the liquid. You take the reading at the BOTTOM of the meniscus. The liquid level is 36.5 mL.

Read these liquid volumes in mL: B. 76.0 mL 11.5 mL