Chapter 1-2: Physics Toolkit

Goal of this course . . . NOT to make you a physicist!  IS to . . . Give you an idea of the way physicists view the world. Understand and even predict the outcome of events around you. Be able to pursue career in a technical field. Be an informed citizen. Learn to ask questions!

a branch of science that involves the study of the physical world Physics – a branch of science that involves the study of the physical world (from electrons to galaxies): energy, matter, and how they are related Ex. Waves, sound, light, magnetism, electricity, motion (kinematics), force (dynamics), and much more . . .

Tools in our Physics Toolkit Scientific Method System International (Metric System) SI Units Calculators! Scientific Notation Significant Figures SI Prefixes

International System of Units Abbreviated SI From the French – Système international d'unités Also known as the metric system. Sometimes called m-k-s system for meters-kilograms-seconds. The system of measuring units based on ten used around the world.

Almost all of modern science is done with the metric system. SI Units Almost all of modern science is done with the metric system. Variable Unit Symbol Length meters m Mass kilograms kg Time seconds s Temperature Kelvin K Amount of a Substance mole mol Electric Current ampere A Luminous Intensity candela cd

These are quantities that are measured directly => fundamental measurements Other quantities can be found by combining two or more of these direct measurements => derived measurements

Measure of time, mass, length, etc. (sec.) (kg) (m) Fundamental Measurements Measure of time, mass, length, etc. (sec.) (kg) (m) Thus the SI units are also called the Fundamental Units. Derived Measurements Measure of density, speed, volume, etc. (kg/m3) (m/s) (m3) Thus these are combinations of SI units.

M x 10n Scientific Notation where is 1≤ M ≤ 10 and n is an integer Physics is exciting because it deals with the very, very small to the very, very large. Numbers can be written . . . M x 10n where is 1≤ M ≤ 10 and n is an integer

Examples & Practice 5.) 560 000 000 m 6.) 0.000 003 5 m Examples: 1.) 810 000 g 2.) 0.000 643 g 3.) 6.0x107 g 4.) 1.0x10-8 g 5.) 5.60x108 m 6.) 3.5x10-6 m 7.) 0.009 24 m 8.) 800 000 m Answers: 1.) 8.1x105 g 2.) 6.43x10-4 g 3.) 60 000 000 g 4.) 0.000 000 010 g 5.) 560 000 000 m 6.) 0.000 003 5 m 7.) 9.24x10-3 m 8.) 8x105 m

Sometimes when dealing with the very, very small or very, very large, instead of using scientific notation, it is easier to use prefixes. For example, measuring the length of an ant, the length of the school, the diameter of the Earth and the distance to the next closest star are all very different sizes. We could use a meterstick for all but there would be a lot of zeros. . . So we use prefixes.

Larger & Smaller ones Factor Name Symbol 10-1 deci d 10-2 centi c 10-3   Factor Name  Symbol 10-1 deci d 10-2 centi c 10-3 milli m 10-6 micro µ 10-9 nano n 10-12 pico p 10-15 femto f 10-18 atto a 10-21 zepto z 10-24 yocto y Factor Name  Symbol 1024 yotta Y 1021 zetta Z 1018 exa E 1015 peta P 1012 tera T 109 giga G 106 mega M 103 kilo k 102 hecto h 101 deka da Ex. Nanotechnology Kilobytes, megabytes, gigabytes, etc.

There are two basic ways to convert from one prefix to another. 1.) The “Down Right Easy Method” This is the moving the decimal method that you learned in middle school. 2.) The “Conversion Method” This is the multiplying by a conversion factor, you learned this in high school. Personally, I think you need both!

Down Right Easy Method kilo- k 1000x hecto- h 100x decka- D 10x base (m, L, g) deci- d 1/10 or 0.1 centi- c 1/100 or 0.01 milli- m 1/1000 or 0.001 Examples: 134 m = km 0.235 hm = cm 8 542 mm = Dm 15.7 Dm = dm 0.134 2 350 0.8542 1 570

Conversion Method Convert 5021 cm to km. 5021cm 1m 1km = 5.021x10-2 km 100cm 1000m or 0.05021 km How many seconds in a leap year? 366 days 24 hours 60 min 60 sec 1 day 1 hour 1 min = 3.16 x 107 sec The conversion factor! The two numbers are equal to each other . . . So it is the same as multiplying by 1.

How many MHz are in 750 kHz. 750 kHz 1000 Hz 1x106 MHz 1 kHz 1 Hz = 0 How many MHz are in 750 kHz? 750 kHz 1000 Hz 1x106 MHz 1 kHz 1 Hz = 0.75 MHz Convert the speed 5.30 m/s to km/h. 5.30 m 1 km 60 s 60 min s 1000 m 1 min 1 hr = 19.1 km/h

Mathematics & Physics Convert each of the following measurements to meters: A.) 42.3 cm B.) 21 km C.) 0.023 mm D.) 6.2 pm E.) 214 mm F.) 57 nm A.) 0.423 m B.) 2.1x104m C.) 2.3x10-5m D.) 6.2x10-12m E.) 2.14x10-4m F.) 5.7x10-8m

Rank the following mass measurements from least to greatest: 11.6 mg 1021 mg 0.000 006kg 0.31 mg 0.31 mg 1021 mg 0.000 006kg 11.6 mg

Significant Figures (Sig Figs) (SF) All measured digits are significant. Zeros may or may not be significant. Sandwiched zeros ARE significant Zeros actually measured ARE significant Place holding zeros are NOT significant Use scientific notation to indicate sig. figs. MULTIPLICATION & DIVISION fewest sig. figs. ADDITION & SUBTRACTION fewest decimal places

State the number of significant figures in each of the following measurements: A.) 0.000 03 m B.) 64.01 fm C.) 80.001 m D.) 0.720 mg E.) 2.40x106 kg F.) 6x108 kg G.) 4.07x1016 m A.) 1 B.) 4 C.) 5 D.) 3 E.) 3 F.) 1 G.) 3

“EE “ = “EXP” = “times ten to the” Calculators! Calculators are ALWAYS allowed. They are your friend, BUT they are only as smart as the operator. YOU must enter the numbers in the correct order of operation. Use the Exponent key!!!!!!!! “EE “ = “EXP” = “times ten to the” P.S. The answer is ALWAYS NO, you may not use your cell phone/other electronic device calculator

Examples & Practice Add or subtract a indicated (in your calculator!). A.) 6.12x109s B.) 2.94x10-6m C.) 1.250x10-4kg D.) 7.50x107g A.) 5.80x109s + 3.20x108s B.) 4.87x10-6m – 1.93x10-6m C.) 3.14x10-5kg + 9.36x10-5kg D.) 8.12x107g – 6.20x106g We actually practiced 3 things here . . . 1.) scientific notation 2.) using our calculators and 3.) significant figures. 

Add or subtract as indicated. E.) 16.2 m +5.008 m + 13.48 m F.) 5.006 m + 12.0077 m + 8.0084 m G.) 78.05 cm2 – 32.046 cm2 H.) 15.07 kg – 12.0 kg E.) 34.7 m F.) 25.022 m G.) 46.00 cm2 H.) 3.1 kg In addition to the things we practiced on the last slide we are also practicing conversions! 

Multiply or divide as indicated. I.) (6.2x1018 m)(4.7x10-10 m) J.) (5.6x10-7 m)/(2.8x10-12 s) K.) (8.1x10-4 km)(1.6x10-3 km) L.) (6.5x105 kg)/(3.4x103 m3) I.) 2.9x109 m2 J.) 2.0x105 m/s K.) 1.3x10-6 km2 L.)1.9x102 kg/m3 In addition to the things we practiced on the last two slide we are also practicing SI units! 

Some of the strategies for studying the physical world are . . . List all possible solutions Look for patterns Construct a table, graph, or figure Make a model Guess & Check Work backwards Make a drawing Solve a simpler or similar problem

These organized strategies lead us to the Scientific Method . . . Before . . . Philosophy People sat around and theorized. After . . . Scientific Method The theories are now tested!

Science and Religion (not vs. they are not competing) Science is about cosmic order Religion is about cosmic purpose

Science is a way of knowing. Technology is a way of doing. Science in general . . . Science is a way of knowing. Technology is a way of doing. Ex. electricity – the science light bulbs & computers - technology

Some people feel that science and technology are bad and harmful ... Make a distinction between the “thing” and the abuse of the “thing” Ex. Medicines – good Drug abuse – bad, the abuse of medicine

Hypothesis not supported There is NO single “Scientific Method,” however all scientists study problems in an organized way. State the problem Gather information Form a hypothesis Test the hypothesis Analyze data Hypothesis not supported Hypothesis supported Draw Conclusions

Tools in our Physics Toolkit Problem Solving . . . 5 steps ALWAYS SHOW YOUR WORK!!! Knowns Unknowns Equations (just variables) Work-equation with numbers plugged in Answer with units and correct sig-figs (Gather information) (State the problem) (Form a hypothesis) (Test the hypothesis) Analyze data Draw Conclusions

What are we trying to find? Example Problem page 91 Knowns: m = 1500 kg a = +3.00 m/s2 What is given in the problem? What are we trying to find? Unknown: F = ? Which equation has those variables in it? Solve for the unknown variable: Equation: F = ma Plug in the values and solve: Work: F = (1500 kg)(+3.00 m/s2) State your answer with unit and correct sig figs.: Answer: F = 4500 N