The Nature of Science Sections 1.2 and 1.3 Chapter 1 The Nature of Science Sections 1.2 and 1.3

Standards of Measurement Units and Standards Standard – the exact quantity that people agree to use to compare measurements.

Precision and Accuracy Precision– describes how close measurements are to each other and how carefully the measurements were made. Accuracy – compares a measurement to the real or accepted value.

International System of Units SI is the accepted version of the metric system based on multiples of ten. It is understood by all scientist throughout the world

International System of Units Each type of SI measurement has a base unit. Length meter (m) Mass kilogram (kg) Time second (s) Electric current ampere(A) Temperature kelvin (K)

International System of Units Amount of substance Mole (mol) Intensity of light candela(cd)

Conversions Prefix Kilo Hecto Deka Unit Deci Centi Milli Symbol 1000 1 Meter .1 .01 .001 1 Liter 1 Gram

Conversions Each prefix differs by a multiple of 10 from the next prefix. When converting between the different units of measure, we look at the number of “jumps” between the prefixes of the two units and then multiply or divide by the powers of 10 accordingly.   Example : Convert 3 km to m Solution: There are 3 “jumps” to the right from kilometer to meter. So, we multiply by 10 3 = 1000 3 km = 3 × 1,000 = 3,000 m Example: Convert 20 mm to cm There is 1 “jump” to the left from millimeter to centimeter So, we divide by 10. 20 mm = 20 ÷ 10 = 2 cm

Conversions You move to the right, then you multiply If you move to the left, then you divide Example : Convert 3 km to m Solution: There are 3 “jumps” to the right from kilometer to meter. So, we multiply by 10 3 = 1000 3 km = 3 × 1,000 = 3,000 m

Conversions Example: Convert 20 mm to cm Solution: There is 1 “jump” to the left from millimeter to centimeter So, we divide by 10. 20 mm = 20 ÷ 10 = 2 cm

Chapter 1 Conversion Activity

Scientific Notation Scientists have developed 'scientific notation' as a shorter method to express very large and very small numbers. Scientific Notation is based on powers of the base number 10. The number 123,000,000,000 in scientific notation is written as: 1.23 x 1011

Scientific Notation The first number 1.23 is called the coefficient. It must be greater than or equal to 1 and less than 10. The second number is called the base which must always be 10 in scientific notation. The exponent indicates the power to which 10 must be raised to bring the number to its proper magnitude.

Scientific Notation To write a very large number in scientific notation: 1. Move the decimal point to the left until after the first digit. (e.g. 1.23 000 000 000) 2. The number of places moved by the decimal point would be the exponent. (e.g. 11) 3. Then drop the zeroes. (e.g.) To enter scientific notation in the calculator, use the EXP key.

Scientific Notation A very small number will have a negative exponent, for example: 0.000 000 00712 will be written as 7.12 × 10-9 To write a very small number in scientific notation: 1. Move the decimal point needs to the right until after the first non-zero digit. (e.g. 7.12) 2. The number of places moved by the decimal point would be the negative exponent. (e.g. -9)

Chapter 1 Scientific Notation Activity

Significant Figures See Handout

Metric System – Another Look Prefix Meaning Kilo- 1000 Hecto- 100 Deka- 10 Meter, Liter, Gram 1 Deci- .1 Centi- .01 Milli- .001

Significant Figures – Another Look Digits from 1-9 are always significant. Zeros between two other significant digits are always significant One or more additional zeros to the right of both the decimal place and another significant digit are significant. Zeros used solely for spacing the decimal point (placeholders) are not significant.

Measuring Distance Length is the distance between two points. The SI unit is meter. Large numbers use Kilometers Small numbers use centimeters or millimeters.

Measuring Volume Volume is the amount of space occupied by an object. Regular shaped objects such as squares and rectangles use Volume – Length x Width x Height (cm3) Liquid Volume – you use Liters or milliLiters 1 mL = 1 cm3

Measuring Matter Mass is a amount of matter the object has. Density – the mass per unit volume of a material. Density = mass / volume (kg/cm3)

Measuring Time and Temperature Time – the interval between two events Use a stopwatch or timer to measure time Temperature – measure of how hot or cold something is Measured o Celsius scale You have to convert it to Kelvin; therefore you add 273 to the Celsius reading. Absolute Zero is 0 kelvin

Communicating with Graphs A Visual Display (Graph) Scientists use graphs because they can easily detect patterns in the data. Line Graphs – show the relationship between the dependent variable changes due to the change in the independent variable. Usually over a period of time

Communicating with Graphs Constructing a Line Graph Choose a scale that makes a graph readable Use the X-axis for the independent variable Use the Y-axis for the dependent variable Make sure all units are the same for each variable

Communicating with Graphs Bar Graphs Comparing information collected by counting Pie Graph Used for displaying percentages, or parts of a whole.