Section 2: Standards of Measurement Chapter 1: The Nature of Science Section 2: Standards of Measurement

Learning Goals Name the prefixes used in SI and indicate what multiple of ten each one represents. Identify SI units and symbols. Convert related SI units.

Units and Standards Standard: exact quantity that people agree to use for comparison.

Measurement Systems Imperial system of measurement Feet Pounds Gallons Only 3 countries do not use the metric system of measurement: U.S.A., Myanmar, and Liberia

Measurement Systems International System of Units (SI): an improved version of the metric system. Understood by scientists worldwide Based on multiples of 10 and uses prefixes to indicate a specific multiple.

Measurement Systems SI Base Units: Length – meters (m) Mass – grams (g) Liquid volume – liters (L) Time – seconds (s)

See the “Metric Toolbox” or Page 15 of your textbook for more Measurement Systems SI Prefixes: Kilo (k) – x1000 Centi (c) – x 0.01 or 1/100 Milli (m) – x 0.001 or 1/1000 See the “Metric Toolbox” or Page 15 of your textbook for more

Measurement Systems Converting between SI Units: Use conversion factors: ratios that are used to change one unit to another

Example There are 1000 mL in 1 L. How many mL are in 3 L?

Factor Label Method Write what you know on the left Write what you want on the right Put a conversion factor in the middle Cancel units on top and bottom Multiply top and divide bottom

Example There are 100 cm in 1 m. How many cm are in 2.75 m?

Example How long, in centimeters, is a 3,075 mm rope?

Let’s Practice!

Measuring Distance Length is measured using a unit appropriate for the distance between two points.

Measuring Distance The SI unit of length is the meter (m). mm cm

Measuring Volume Volume: the amount of space an object occupies. The base unit for liquid volume is liters (L) Beakers, flasks, and graduated cylinders (mL)

Measuring Volume Measuring solid volumes: Formulas: (V = l x w x h) Units in cubic centimeters (cm3) or cubic meters (m3) Water displacement

Measuring Matter Mass: a measurement of the quantity of matter in an object. Base unit is grams (g) Balances can be used to measure mass

Measuring Matter Density: the mass per unit volume of a material. How much mass an object has in a certain amount of space. Density = mass/volume Unit for density is grams per milliliter (g/mL)

Measuring Time and Temperature SI unit of time = seconds (s) Metric unit of temperature = degrees Celsius (°C) SI unit of temperature = Kelvin (K)