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Basics of Physics Science • Study of energy flow and energy transfer through living and non-living systems Physics • Study of matter, energy and space and the relationships between them • Explain how the physical world works • 3 major areas • Concepts & calculations Major Topic Areas • Kinematics & Mechanics – motion caused by forces • Waves – Sound, light and optics • Electricity & Magnetism – fields, electric current, circuits, electromagnetism Concepts & Calculations • Concepts – Fundamental laws, theorems and principles which explain and govern physical phenomena and interactions • Calculations – Mathematical formulas & equations (all algebraic) which quantify the relationships between variables Problem Solving Procedure • Read the problem carefully • Draw a simple diagram • Write down all numerical data, both given and assumed • Write down what problem is asking you to solve • Determine equation or formula required for solution – write it down • Rewrite equation with #’s inserted • Perform arithmetic & algebraic operations – show full process in homework & on tests • Include correct units with answer Notebook Homework Format #3 Answers and process for Practice Problems in back of textbook 11) 11) 5.5 km tan 2=192/x x =192/tan2 transparency Chapter 1 A Physics Toolkit SI Units of Measurement • Base units – Length – Mass – Time meter kilogram second (m) (kg) (s) • All lab measurements and answers to problems must have a number and correct units • Smoots SI Metric Prefixes • Factors making unit << 1 – micro – milli m – centi c 106 103 102 Example g ms cm • Factors making unit >> 1 – kilo k – mega M – giga G 103 106 109 kg MHz GByte Unit Conversions • Unit cancellation method – dividing identical units = 1 • Create unit pathway (example on board) • Determine correct conversion factors to use • Insert #’s next to units • Convert 10 mm to m (board) • Convert 50 km/hr to m/s Graphing Data line of best fit animation clip 1-3 Creating a Scientific Graph 1. Determine which is independent variable (you control) and dependent variable (you measure) 2. Label x axis with independent variable – NAME & UNITS 3. Label y axis with dependent variable – name & units 4. Determine total range of data for x axis: 0 to max value. Divide this into equal increments so that most of axis is used. Spread out the data 5. Determine how many divisions (boxes) on x axis will represent that increment. Increments must be equal for the entire axis. Never plot data points on the axis. 6. Repeat steps 4,5 for y axis. Spread out the data. 7. Divisions do not have to be the same on both axes. Scientific Graphs 8. Do not put breaks in the numbers on either axis – always start at 0 and have continuity of numbers from 0 to maximum value on that axis 9. Determine if origin (0,0) is valid even though not measured. Plot if valid. 10. Plot each data point – neatness counts – pencil recommended. Data point labels not necessary 11. Draw best fit line or smooth curve that fits the data – DO NOT CONNECT DOT-TO-DOT!! You may be using this best fit line or curve for calculations and conclusions. 12. No computer generated graphs will be accepted. Do them by hand on the graph sheets given in lab report. Linear relationship • as independent variable increases the dependent variable also increases at a constant rate • straight line • equation form: y=mx+b m rise y2 y1 run x2 x1 m 16.0 14.1cm cm .076 30 5 gram gram • calculate slope using the value of the rise and run • include correct units • never calculate slope using only 4boxes m 5boxes 0.8 LINE OF BEST FIT y • approximately as many data points above the line as below the line • GREEN line is line of best fit • can use it to calculate slope • RED line is incorrect x •don’t connect the dots • it is not a line Quadratic relationship • as the independent variable increases the dependent variable increases at an ever-growing rate • shape of graph is a parabola • Red line is NOT correct – this is NOT a line of best fit • equation form: y=ax2+bx+c Inverse relationship • as the independent variable increases the dependent variable decreases • NOT exponential or quadratic • shape is hyperbola • equation form: a y a is a constant x or xy = a example on board Physics Lab Experiments • Safety is #1 priority • Any equipment loss or breakage at a table due to carelessness will result in detention for all bench members • Lab days are good days not play days • Always start by reading Introduction and then Procedure, do not start at Data Table first. • Reading and following directions is very important • Complete all data collection before beginning calculations or graphing • Lab experiments are not tests. Mr. B will answer questions about procedure AFTER you have read, discussed and thought about the instructions Lab experiments • Communication & cooperation – work as a team; allow multiple members to make measurements; should not have 1 worker and 3 spectators – question and talk to each other – double check calculations if time permits – help each other to get best results possible – listen carefully and take notes during Mr. B’s preview in class • No lab book; lab sheets given out on day of lab; only one copy per person • Pencils highly recommended; points deducted for sloppy lab reports • Clean up and return lab bench to original condition • Lab reports ALWAYS due at the beginning of the next class