TOPIC 1: PHYSICS AND MEASUREMENT IB SL PHYSICS GARCIA GOHS

TOPIC 1.1: The Realm of Physics Magnitude: Estimations of size, often using powers of ten. Useful when dealing with very large/small amounts Make comparisons to known amounts

Magnitude exercises How high is a two-story house in meters? Solution: How high is the ceiling compared to you? How tall are you? Approx. height of room then multiply by two.

1.2 Measurement and Uncertainties S.I. system of measurement “Systeme International” Fundamental: base units Derived: two or more base units combined

1.2 Measurement and Uncertanties Units Metric system Accuracy vs. Precision Significant Figures in calculations

Fundamental SI units

Derived SI units Name Symbol Concept Broken down to base units Newton Force or weight Kgms-2 Hertz Hz Frequency 1/s or s-1 Joule J Energy or work Kgm2s-2

Conversion Factors Conversion Factor: ratio of equal units to convert from one unit to the other. 4 quarters/1 dollar = 1; etc… Factor Label Method: units used for mathematical conversion of measurements 12 dollars (4 quarters/1 dollar) = ? Answer = 48 quarters

Converting Units To convert units: Measured Amount (Conversion Factor) = New Unit

Metric Prefixes

Using Metric Conversion Factors When using the metric table for conversion factor remember: The base unit gets the exponent (base unit is the unit without a prefix) The prefix gets the number 1 Example: 9 m  ? mm Chart says 10-3  milli- Convert: 9 m (1 mm/10-3 m) = 9000 mm

Uncertainty and Error Accuracy: how close a measurement is to the accepted value. Precision: is the degree of exactness of a measurement; consistency in measurement. Uncertainty: the measure of confidence in a measurement. A lower uncertainty indicates greater confidence.

Significant Figures (Sig Figs) Determining Sig Figs: Garcia paraphrase All nonzero digits are significant Zero is significant IF: Between nonzero digits Right of nonzero digits AND there’s a decimal in the number

Sig Figs cont. Addition & Subtraction: Keep the least accurate decimal place. Example: 25.1 + 2.03 = 27.13 = 27.1 5400 + 365.5 = 5765.5 = 5766

Sig Figs cont. Multiplication and Division Keep the least significant figures Example: 3.05 g/8.470 mL = 0.36009445 g/mL = 0.360 g/mL Conversion factors are not included for sig figs

Scientific Notation Used to represent large or small numbers General form: M x 10n 1 < M < 10 n is an integer (+ or - whole number) Example: 602000000000000000000000 = 6.02 x 1023 0.00000000602 = 6.02 x 10-9

Graphing Practice to come later.