1 / 81

Scientific

Scientific. Method. Mass vs. Weight. First we will define Matter… Matter – anything that has mass & takes up space Mass – measurement that tell how much matter you have (kg) Weight – measurement of the amount of matter you have with the effect of gravity. For Example….

caldwellsusan
Télécharger la présentation

Scientific

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Scientific Method

  2. Mass vs. Weight • First we will define Matter… • Matter – anything that has mass & takes up space • Mass– measurement that tell how much matter you have (kg) • Weight – measurement of the amount of matter you have with the effect of gravity

  3. For Example… • Let’s say a guy weighs 150 pounds • This is about 54 kg in mass • What would his mass be on the moon if the moon’s gravity is about 1/6 that of the Earth?

  4. Hmmmm… • Would it be 1/6 of 150 pounds? • Would it be 1/6 of 54 kg? • Would it be 150 pounds • Or would it be 54 kg? The answer is … 54 kg

  5. Some of you are scratching your heads… • The reason is because gravity has NOTHING to do with mass – that’s only for weight • His mass did not change only his weight changed

  6. The Scientific Method • Scientific Method – a systematic approach used in scientific study • It is an organized approach for scientists to do research • Provides a method for scientists to verify their work and the work of others

  7. Steps for the Scientific Method Step # 1 – Observation • Observation – the act of gathering information (data) • Qualitative data – information with NO numbers • (hot, blue, rainy, cold) • Quantitative data – information with numbers • (98°F, 80% humidity, 0°C)

  8. Steps for the Scientific Method Step # 2 – Form a Hypothesis • Hypothesis – tentative explanation for what has been observed • There is no formal evidence at this point • It is just a gut feeling

  9. Steps for the Scientific Method Step # 3 – ExperimentationExperimentation – a set of controlled observations that test the hypothesis • Independent variable – the thing that you change in the experiment • Dependant variable – the thing that changes because you changes the independent variable • Constant – something that does not change during the experiment • Control – the standard for comparison

  10. For example… • Let’s say we are going to do an experiment testing what happens when you heat and cool a balloon… We will start with a balloon at room temperature

  11. Now we will change something… I will add heat to one balloon It will expand What will happen to the balloon’s size?

  12. Now let’s cool things down I will add cool down the balloon It will get smaller What will happen to the balloon’s size?

  13. So what is what? (Independent Variable) • What variable did YOU change? • Temperature • What variable changes BECAUSE you changed the temperature? • Size of the balloon • What is did not change in the experiment? • Amount of air in the balloon, what the balloon is made of… • What balloon did you use to compare the others to? • The room temperature balloon (Dependent Variable) (Constant) (Control)

  14. Steps for the Scientific Method Step # 4 – Conclusion • Conclusion – judgment based on the information obtained

  15. Introduction to Significant Figures& Scientific Notation

  16. Significant Figures • Scientist use significant figures to determine how precise a measurement is • Significant digits in a measurement include all of the known digits plus one estimated digit

  17. For example… • Look at the ruler below • Each line is 0.1cm • You can read that the arrow is on 13.3 cm • However, using significant figures, you must estimate the next digit • That would give you 13.30 cm

  18. Let’s try this one • Look at the ruler below • What can you read before you estimate? • 12.8 cm • Now estimate the next digit… • 12.85 cm

  19. The same rules apply with all instruments • The same rules apply • Read to the last digit that you know • Estimate the final digit

  20. Let’s try graduated cylinders • Look at the graduated cylinder below • What can you read with confidence? • 56 ml • Now estimate the last digit • 56.0 ml

  21. One more graduated cylinder • Look at the cylinder below… • What is the measurement? • 53.5 ml

  22. Rules for Significant figuresRule #1 • All non zero digits are ALWAYS significant • How many significant digits are in the following numbers? • 3 Significant Figures • 5 Significant Digits • 4 Significant Figures • 274 • 25.632 • 8.987

  23. Rule #2 • All zeros between significant digits are ALWAYS significant • How many significant digits are in the following numbers? 3 Significant Figures 5 Significant Digits 4 Significant Figures 504 60002 9.077

  24. Rule #3 • All FINAL zeros to the right of the decimal ARE significant • How many significant digits are in the following numbers? 3 Significant Figures 5 Significant Digits 7 Significant Figures 32.0 19.000 105.0020

  25. Rule #4 • All zeros that act as place holders are NOT significant • Another way to say this is: zeros are only significant if they are between significant digits OR are the very final thing at the end of a decimal

  26. 0.0002 6.02 x 1023 100.000 150000 800 1 Significant Digit 3 Significant Digits 6 Significant Digits 2 Significant Digits 1 Significant Digit For example How many significant digits are in the following numbers?

  27. Rule #5 • All counting numbers and constants have an infinite number of significant digits • For example: 1 hour = 60 minutes 12 inches = 1 foot 24 hours = 1 day

  28. 0.0073 100.020 2500 7.90 x 10-3 670.0 0.00001 18.84 2 Significant Digits 6 Significant Digits 2 Significant Digits 3 Significant Digits 4 Significant Digits 1 Significant Digit 4 Significant Digits How many significant digits are in the following numbers?

  29. Rules Rounding Significant DigitsRule #1 • If the digit to the immediate right of the last significant digit is less that 5, do not round up the last significant digit. • For example, let’s say you have the number 43.82 and you want 3 significant digits • The last number that you want is the 8 – 43.82 • The number to the right of the 8 is a 2 • Therefore, you would not round up & the number would be 43.8

  30. Rounding Rule #2 • If the digit to the immediate right of the last significant digit is greater that a 5, you round up the last significant figure • Let’s say you have the number 234.87 and you want 4 significant digits • 234.87 – The last number you want is the 8 and the number to the right is a 7 • Therefore, you would round up & get 234.9

  31. 200.99 (want 3 SF) 18.22 (want 2 SF) 135.50 (want 3 SF) 0.00299 (want 1 SF) 98.59 (want 2 SF) 201 18 136 0.003 99 Let’s try these examples…

  32. Significant Digits Calculations

  33. Significant Digits in Calculations • Now you know how to determine the number of significant digits in a number • How do you decide what to do when adding, subtracting, multiplying, or dividing?

  34. Rules for Addition and Subtraction • When you add or subtract measurements, your answer must have the same number of decimal places as the one with the fewest • For example: 20.4 + 1.322 + 83 = 104.722

  35. Addition & Subtraction Continued • Because you are adding, you need to look at the number of decimal places 20.4 + 1.322 + 83 = 104.722 (1) (3) (0) • Since you are adding, your answer must have the same number of decimal places as the one with the fewest • The fewest number of decimal places is 0 • Therefore, you answer must be rounded to have 0 decimal places • Your answer becomes • 105

  36. 1.23056 + 67.809 = 23.67 – 500 = 40.08 + 32.064 = 22.9898 + 35.453 = 95.00 – 75.00 = 69.03956  69.040 - 476.33  -476 72.1440  72.14 58.4428  58.443 20  20.00 Addition & Subtraction Problems

  37. Rules for Multiplication & Division • When you multiply and divide numbers you look at the TOTAL number of significant digits NOT just decimal places • For example: 67.50 x 2.54 = 171.45

  38. Multiplication & Division • Because you are multiplying, you need to look at the total number of significant digits not just decimal places 67.50 x 2.54 = 171.45 (4) (3) • Since you are multiplying, your answer must have the same number of significant digits as the one with the fewest • The fewest number of significant digits is 3 • Therefore, you answer must be rounded to have 3 significant digits • Your answer becomes • 171

  39. 890.15 x 12.3 = 88.132 / 22.500 = (48.12)(2.95) = 58.30 / 16.48 = 307.15 / 10.08 = 10948.845  1.09 x 104 3916.977  3917.0 141.954  142 3.5376  3.538 30.47123  30.47 Multiplication & Division Problems

  40. 18.36 g / 14.20 cm3 105.40 °C –23.20 °C 324.5 mi / 5.5 hr 21.8 °C + 204.2 °C 460 m / 5 sec = 1.293 g/cm3 = 82.20 °C = 59 mi / hr = 226.0 °C = 90 or 9 x 101 m/sec More Significant Digit Problems

  41. Scientific Notation • Scientific notation is used to express very large or very small numbers • I consists of a number between 1 & 10 followed by x 10 to an exponent • The exponent can be determined by the number of decimal places you have to move to get only 1 number in front of the decimal

  42. Large Numbers • If the number you start with is greater than 1, the exponent will be positive • Write the number 39923 in scientific notation • First move the decimal until 1 number is in front – 3.9923 • Now at x 10 – 3.9923 x 10 • Now count the number of decimal places that you moved (4) • Since the number you started with was greater than 1, the exponent will be positive • 3.9923 x 10 4

  43. Small Numbers • If the number you start with is less than 1, the exponent will be negative • Write the number 0.0052 in scientific notation • First move the decimal until 1 number is in front – 5.2 • Now at x 10 – 5.2 x 10 • Now count the number of decimal places that you moved (3) • Since the number you started with was less than 1, the exponent will be negative • 5.2 x 10 -3

  44. 99.343 4000.1 0.000375 0.0234 94577.1 9.9343 x 101 4.0001 x 103 3.75 x 10-4 2.34 x 10-2 9.45771 x 104 Scientific Notation Examples Place the following numbers in scientific notation:

  45. Going from Scientific Notation to Ordinary Notation • You start with the number and move the decimal the same number of spaces as the exponent. • If the exponent is positive, the number will be greater than 1 • If the exponent is negative, the number will be less than 1

  46. 3 x 106 6.26x 109 5 x 10-4 8.45 x 10-7 2.25 x 103 3000000 6260000000 0.0005 0.000000845 2250 Going to Ordinary Notation Examples Place the following numbers in ordinary notation:

  47. Conversions And Density Problems

  48. Accuracy vs. Precision • Accuracy – How close you are to the correct answer • Precision – How close your answers are together

  49. For Example… • Let’s say we had the following dart board Is the accuracy good or bad? Accuracy - GOOD Precision - GOOD Is the precision good or bad?

  50. Try this one • Let’s say we had the following dart board Is the accuracy good or bad? Accuracy - BAD Precision - GOOD Is the precision good or bad?

More Related