Chapter 1 The Nature of Science 1.2 Standards of Measurement In science, why is it important that measurements are standardized? When you get results of an experiment, how do you know if they are precise or accurate? Whats the difference? 1.2 Standards of Measurement To ensure that results can be easily understood, a common system of units of measurements are used This is called the International System, or SI for short (from the French Le system internationale dUnites)
Each type of SI measurement has a base unit and prefixes based on multiples of 10 Why would this system be widely used, especially in science? KNOW THESE!!! 1.2 Standards of Measurement Measuring Distance Base unit: meter (m) Slightly longer than a yard So would your time for a 100-m dash be slightly more or less than your time for a 100-yard dash? Choose an appropriate unit
Measuring the distance from the earth to the moon is better measured in kilometers (km) than in centimeters (cm) or meters (m) 1.2 Standards of Measurement Choose the most appropriate distance measurement for each: 1.2 Standards of Measurement Measuring Distance Reading a metric ruler 1.2 Standards of Measurement Measuring Volume
Volume is the amount of space occupied by an object Volume of a solid rectangle: length x width x height Final volume in in (units) If I had a brick that was 6 cm long, 4 cm wide, and 3 cm tall, what would its volume be? Liquid Volume Use liters (L) or milliliters (mL) 1 mL = 1 cm 1.2 Standards of Measurement Measuring Matter
Mass is a measurement of the quantity of matter in an object Base unit: gram (g) How do mass and weight differ? Mass is a measurement of the amount of matter something contains Weight is the measurement of the pull of gravity on an object Measuring Mass We will be using triple-beam balances to find the mass of various objects. The objects are placed on the scale and then you move the weights on the beams until you get the lines on the right-side of the scale to match up. Once you have balanced the scale, you add up the amounts on
each beam to find the total mass. What would be the mass of the object measured in the picture? _______ + ______ + _______ = ________ g 1.2 Standards of Measurement Measuring Matter Density Mass per unit volume of a material Density = mass divided by volume d=m/v Typically expressed in grams/centimeter or grams/milliliter Remember 1 cm = 1 mL
What is the density of an object that has a mass of 10 g and a volume of 2 cm? 1.2 Standards of Measurement Measuring Time and Temperature Time: measured in seconds Temperature: typically measured in Celsius (C) Freezing = 0C Boiling = 100C Human body temperature = 37C Sometimes temperature is measured in Kelvin (K) Absolute Zero (0 K) = the coldest possible temperature
To convert Celsius to Kelvin, add 273 to the Celsius reading Practice: Convert 27C to Kelvin. 1.2 Conversions Ladder Method 1 2 KILO 1000 Units HECTO 100
Units 3 DEKA 10 Units Meters Liters Grams How do you use the ladder method? 1st Determine your starting point. 2nd Count the jumps to your ending point. 3rd Move the decimal the same number of jumps in the same direction.
DECI 0.1 Unit CENTI 0.01 Unit MILLI 0.001 Unit 4 km = _________ m Starting Point
Ending Point How many jumps does it take? 4. __. 1 2 . . = 4000 m __ __ 3
Conversion Practice Meters Liters Grams Try these conversions using the ladder method. 1000 mg = _______ g 1 L = _______ mL 160 cm = _______ mm 14 km = _______ m 109 g = _______ kg
250 m = _______ km Compare using <, >, or =. 56 cm 6m 7g 698 mg Write the correct abbreviation for each metric unit. 1) Kilogram _____
4) Milliliter _____ 7) Kilometer _____ 2) Meter _____ 5) Millimeter _____ 8) Centimeter _____ 3) Gram _____ 6) Liter _____ 9) Milligram _____
Try these conversions, using the ladder method. 10) 2000 mg = _______ g 15) 5 L = _______ mL 20) 16 cm = _______ mm 11) 104 km = _______ m 16) 198 g = _______ kg 21) 2500 m = _______ km 12) 480 cm = _____ m
17) 75 mL = _____ L 13) 5.6 kg = _____ g 14) 8 mm = _____ cm 18) 50 cm = _____ m 19) 5.6 m = _____ cm 22) 65 g = _____ mg 23) 6.3 cm = _____ mm 24) 120 mg = _____ g