Chapter 2 Data Analysis

What’s wrong with this sign?

Temperature 30°C 30°F

Système Internationale d’ Unités SI unit

Prefixes used with SI units

English vs. Metric Units Which is longer? A. 1 mile or 1 kilometer B. 1 yard or 1 meter C. 1 inch or 1 centimeter 1.6 kilometers 1 mile 1 yard = 0.9444 meters 1 inch = 2.54 centimeters Left Image: http://webapps.lsa.umich.edu/physics/demolab/controls/imagedemosm.aspx?picid=1167 Right Image: http://share.lancealan.com/N800%20ruler.jpg

m km mm cm Metric Units of Length The basic unit of length in the metric system in the meter and is represented by a lowercase m. Metric Units 1 Kilometer (km) = 1000 meters 1 Meter = 100 Centimeters (cm) 1 Meter = 1000 Millimeters (mm) Which is larger? A. 1 meter or 105 centimeters B. 4 kilometers or 4400 meters C. 12 centimeters or 102 millimeters D. 1200 millimeters or 1 meter

1 centimeter = 10 millimeters Measuring Length How many millimeters are in 1 centimeter? 1 centimeter = 10 millimeters What is the length of the line in centimeters? _______cm What is the length of the line in millimeters? _______mm What is the length of the line to the nearest centimeter? ________cm

English vs. Metric Units 1 pound = 453.6 grams Which is larger? 1. 1 Pound or 100 Grams 2. 1 Kilogram or 1 Pound 3. 1 Ounce or 1000 Milligrams 1 kilogram = 2.2 pounds 1 ounce of gold = 28,349.5 milligrams

Kilogram Prototype Image - http://en.wikipedia.org/wiki/Kilogram Metric Units of mass kg mg g Mass refers to the amount of matter in an object. The base unit of mass in the metric system in the kilogram and is represented by kg. Metric Units 1 Kilogram (km) = 1000 Grams (g) 1 Gram (g) = 1000 Milligrams (mg) Which is larger? A. 1 kilogram or 1500 grams B. 1200 milligrams or 1 gram C. 12 milligrams or 12 kilograms D. 4 kilograms or 4500 grams Kilogram Prototype Image - http://en.wikipedia.org/wiki/Kilogram

English vs. Metric Units Which is larger? A. 1 liter or 1 gallon B. 1 liter or 1 quart C. 1 milliliter or 1 fluid ounce 1 fl oz = 29.573 ml 1 12-oz can of soda would equal approximately 355 ml. 1 gallon = 3.79 liters It would take approximately 3 ¾ 1-liter bottles to equal a gallon. 1 quart = 0.946 liters

Metric Units kL cL mL L Volume is the amount of space an object takes up. The base unit of volume in the metric system in the liter and is represented by L or l. Metric Units 1 liter (L) = 1000 milliliters (mL) 1 milliliter (mL) = 1 cm3 (or cc) = 1 gram* Which is larger? A. 1 liter or 1500 milliliters B. 200 milliliters or 1.2 liters C. 12 cm3 or 1.2 milliliters*

Measuring Volume We will be using graduated cylinders to find the volume of liquids and other objects. Read the measurement based on the bottom of the meniscus or curve. When using a real cylinder, make sure you are eye-level with the level of the water. What is the volume of water in the cylinder? _____mL What causes the meniscus? A concave meniscus occurs when the molecules of the liquid attract those of the container. The glass attracts the water on the sides.

Measuring Liquid Volume What is the volume of water in each cylinder? Images created at http://www.standards.dfes.gov.uk/primaryframework/downloads/SWF/measuring_cylinder.swf A B C Pay attention to the scales for each cylinder.

Measuring Solid Volume 10 cm 9 cm 8 cm We can measure the volume of regular object using the formula length x width x height. _____ X _____ X _____ = _____ http://resources.edb.gov.hk/~s1sci/R_S1Science/sp/en/syllabus/unit14/new/testingmain1.htm We can measure the volume of irregular object using water displacement. Amount of H2O with object = ______ About of H2O without object = ______ Difference = Volume = ______

Temperature Scales How hot? How cold? direction of Heat Transfer Celsius – 0 0C Freezing Point of Water 100 0C Boiling Point of Water Kelvin = C° + 273 No degree signs are used O Kelvin = -273.150 C coldest possible temperature

What is the metric unit for…? Length – size meter (m) Mass – amount of matter Kilogram (kg) or gram (g) Volume – space something takes up Liter (l) or centimeters cubed (cm3) Temperature – amount of heat Kelvin (K) = celsius + 273

Density Measure of how much matter is squeezed into a given space density = mass volume

Which one is more dense? A block of wood and a block of steel have the same volume

What do you think? What happens to the density of an object if it is cut into pieces? Which has the greater density, a single uranium atom or Earth?

Scientific Notation coefficient x 10 raised to a power Single gram of hydrogen 602,000,000,000,000,000,000,000 molecules = 6.02 x 1023 molecules Mass of an atom of gold 0.000000000000000000000327 grams = 3.27 x 10-22 grams

Practice 36,000 3.6 x 104 503,000,000 5.03 x 108 0.00076 7.6 x 10-4

The valid digits of a number Significant Figures The valid digits of a number   In measurement: includes all of the digits that are known, plus a last digit that is estimated

Significant Figures Significant: Not significant nonzero digits final zeros after the decimal points zeros between two other significant digits Not significant zeros used solely for spacing the decimal point are not significant.

Examples each have only two sig figs 7.1 x 10-3 meter 4.2 x 10-1 meter

# of significant figures Value 5.60 5.6 0.012 0.0012003 0.0120 0.0012 # of significant figures 3 2 5

Rounding If the digit immediately to the right of the last significant digit is less than 5, it is dropped 5 or greater - last significant digit increased by 1 41.58 square meters  41.6 square meters

Practice Round 65.145 meters to 4 sig figs Round 100.1°C to 1 sig fig Round 154 cm to 2 sig figs 150 Round 0.000718 kilograms to 2 sig figs 0.00072

Measurements with an Unlimited Number of Significant Digits Counting Example: 23 people in the classroom (Not 22.9 or 23.1) 23.00000000………………. Exactly defined quantities Example: 60 minutes = 1 hour 60.00000000……………………..

Calculation Rules calculated answer cannot be too precise not more precise than the least precise measurement Multiplication and Division same number of sig figs as the measurement with the least number of sig figs Addition and Subtraction same number of decimal places as the measurement with the least number of decimal places

Accuracy and Precision How close a measurement comes to the actual value of what is being measured Precision How close a series of measurements are to one another

Error Difference between accepted value and experimental value error = experimental value – accepted value % error = x 100% error accepted value

Error % error = x 100% 99.1°C – 100.0°C x 100% 100.0°C 0.9°C x 100% 0.9% error accepted value = = =