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Chapter 0

Chapter 0. Scientific Method and Measurement. The Method. What organized method do scientists use to solve a problem?. The scientific method Define the problem Make a hypothesis Make observations Record data Review the data Modify hypothesis Retest. The Method.

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Chapter 0

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  1. Chapter 0 Scientific Method and Measurement

  2. The Method • What organized method do scientists use to solve a problem? • The scientific method • Define the problem • Make a hypothesis • Make observations • Record data • Review the data • Modify hypothesis • Retest

  3. The Method • What is the definition of… • Hypothesis? • Variable? • Control? • Qualitative Data? • Quantitative Data? • A prediction or guess • What changed • Stays the same • Non-numerical (ex. Blue) • Numerical (ex. 55 cm)

  4. The Method • Why is it important not to have too many variables? • Hard to tell which, if any, variables affected the result • Limit the variablesand have lots of controls

  5. Theory vs. Law • What is the main difference between a theory and a law? • A law is a (mathematical) relationship that predicts what happens and is always correct. • A theory is an evolving body of information. It has not been proven correct.

  6. Airplane Challenge • I challenge your team to build a paper airplane that will FLY the farthest distance. • Each team will build three planes. • 3 pieces of paper, 6 paper clips, scissors • Your team will test ONE variable to see which of your three prototypes will work the best. • In your observations, you must list at least 3 controls and 1 variable.

  7. Airplane Challenge Before you fly! • What am I testing? • What is my first hypothesis? • What are 3 controls and my 1 variable? After you fly! • What did I observe after the test flights? • Please answer these questions in your notebook.

  8. Precision vs. Accuracy • What is the difference between precision and accuracy? • Accuracy refers to how close it is to the correct value • Precision refers to how close together a group of measurements are to each other

  9. Precision vs. Accuracy • On the right hand side of your notes, please draw the following targets with the bullet holes.

  10. Precision vs. Accuracy • Label the target that is accurate and precise.

  11. Precision vs. Accuracy • Label the target that is the least precise.

  12. Precision vs. Accuracy • Label the target that is precise and inaccurate.

  13. Practice Problem #1 • An archer shoots three arrows at a target and each land within 1 cm of each other, but none of the arrows are within 30 cm of the center. • Explain whether the archer is precise, accurate, neither or both.

  14. Practice Problem #2 • The table lists the results of temperature measurements of a beaker of boiling water. The temperature of boiling water is 100 °C. • Explain whether each thermometer was accurate, precise, neither or both.

  15. Precision and Measurement • Pick the measuring device that makes the most sense: stick, book or paper clip • Measure the object or area. • Estimate the final value. (ex. 0.5, quarter, 1/3) • Record your measurements in the table.

  16. Precision and Measurement • Which measurement do I feel is the most precise and WHY? • What is one benefit AND one drawback to using a smaller unit of measurement?

  17. Scientific Notation • What is scientific notation? • A shortcut for writing really large or really small numbers • Every number can be represented by a number between 1 and 10 and multiplied by a power of 10

  18. Scientific Notation • What are some examples of scientific notation? • Large numbers • 190,000,000 • 1.9 x 108 • Small number • 0.000567 • 5.67 x 10-4

  19. Scientific Notation • How do I do scientific notation? • Put a decimal after the first non-zero number • Count the number of spaces the decimal place moved • If the decimal moved to the left, the exponent is positive and if it moved to the right its negative • Drop unwanted zeros

  20. Scientific Notation • What is 35600 in scientific notation? • What is 0.000721 in scientific notation? • 3.56 x 104 • Zeros at the end dropped • 7.21 x 10-4 • Zeros at the beginning dropped

  21. Scientific Notation Practice • Please convert the following into proper scientific notation: • 784000 • 100 • 0.023498 • -4321 • 0.0000006 • 1.30 • 7.84 x 105 • 1 x 102 • 2.3498 x 10-2 • -4.321 x 103 • 6 x 10-7 • 1.30

  22. Scientific Notation Reversed • Please convert the following into standard format: • 5.68 x 103 • 2.1 x 10-5 • 4.309 x 102 • 5680 • 0.000021 • 430.9

  23. Scientific Notation and Calculators • What buttons are used on a calculator for scientific notation? • Its usually either… • EE -or- • exp

  24. Scientific Notation and Calculators • What may show up on my screen? • On your screen, you may see the following: • X10 exponent • E exponent • (space) exponent

  25. Scientific Notation and Calculators • Put the following number into your calculator and hit equals/enter: 4.56 x 1015 • Please understand that you will need to translate this into proper notation!

  26. Scientific Notation and Calculators • Using your calculator, determine the following answers in scientific notation: Multiply: • (4.57 x 10-3)(2.0 x 105) Divide • (3.1 x 103)/(4.7x105) • 914 • 0.0066

  27. Scientific Notation • What power are you multiplying and dividing by each time you move a decimal? • Powers of 10 • These powers allow us to comprehend very large (size of galaxies) and very small (size of atoms) numbers

  28. Dimensional Analysis Why is dimensional analysis important? It allows us to easily convert between units using a series of equivalent fractions

  29. Dimensional Dominoes - Colors • With your team, set up the color dominoes to convert the following colors into new ones. • Convert cowpoke brownto deeply red • Convert cowpoke brownto pink glitz • Convert black leather to orange sizzle • Convert orange sizzle to black leather • Convert cowpoke brown to Houdini blue

  30. Dimensional Dominoes - Units • The English unit, the rod, is equal to 16.5 ft. What is this length expressed in meters? • Directions: With your team, set up the unit dominoes to convert the following units into new ones then copy the set-up into your notes (right side). Answer = 5.03 meters

  31. Dimensional Dominoes - Units • The portage trails on maps are measured and marked in rods. On a recent canoe trip to the Skagit and Cascade Rivers my brother and I portaged a total of 2342 rods. How many total miles did we carry our gear? • Directions: With your team, set up the unit dominoes to convert the following units into new ones then copy the set-up into your notes. Answer = 7.3 miles

  32. Dimensional Dominoes - Units • If a college student smokes an average of 10 cigarettes per day for five years of school, how much money will they have spent on smokes by the time they graduate? • Directions: With your team, set up the unit dominoes to convert the following units into new ones then copy the set-up into your notes. Answer = $ 4106.25

  33. Dimensional Dominoes - Units • The weight of bullets and arrows is measured in a unit called the grain. If an arrow weighs 330 grains what is its weight in ounces? • Directions: With your team, set up the unit dominoes to convert the following units into new ones then copy the set-up into your notes. Answer = 0.775 ounces

  34. Dimensional Dominoes - Units • Assuming that you attend school 180 days a year for 8 hours a day from first through twelfth grade, you’d be in class for a total of 2160 school days. How many total years of your life will you have spent in school by the time you graduate? • Directions: With your team, set up the unit dominoes to convert the following units into new ones then copy the set-up into your notes. Answer = 1.97 years

  35. Dimensional Dominoes - Units • How many pounds does a 5 gallon pail of water weight? • Directions: With your team, set up the unit dominoes to convert the following units into new ones then copy the set-up into your notes. Answer = 41.62 pounds

  36. Dimensional Analysis • What is a base unit? • What is a prefix? • Basic unit from which all other units are created • Ex. Length – meters • Ex. Mass – grams • Goes in front of a base unit to indicate how many • Ex. Length – kilometers • Ex. Mass – milligrams

  37. Dimensional Analysis How many different types are there? • Three types: • Two step - converting to or from a base unit • Ex. m to km • Three step - converting from a non-base unit to a non-base unit • Ex. mm to km • Non-metric – converting between different scales

  38. Dimensional Analysis - Two Step • Please convert 5 kilograms to grams. • First fraction is what we have: • Second fraction is what we want: • Remember… The unit with the prefix gets the one! • Multiply across the top and bottom and then divide.

  39. Dimensional Analysis - Two Step • Please convert: • 2.5 cm to m • 0.04 J to kJ • 3.5 g to mg • 0.5 L to cL • 3.1 x 104mL to L • 50.8 g to ng

  40. Dimensional Analysis - Three Step • Please convert 92 kilograms to milligrams. • First fraction is what we have: • Second fraction is the conversion to the base unit: • Third fraction is what we want: • Calculate the same way as before

  41. Dimensional Analysis - Three Step • Please convert: • 36.0 cm to km • 52 kg to mg • 601 mL to cL • 0.003 dg to cg • 8 μg to mg • 0.00036 km • 52000000 mg • 60.1 cL • 0.03 cg • 0.008 mg

  42. Dimensional Analysis – Non-metric • What is a non-metric conversion? • Use math formulas • Ex. Temperature • Use other equivalencies • Ex. 12 inches = 1 foot

  43. Dimensional Analysis – Non-metric • Please convert: • 34 inches to feet • 2 atm to Pa • 15 °C to °F • 5 L to gallons • 2000 calories to J • 2.8 ft • 202650 Pa • 59 °F • 1.32 gallons • 8368 J

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