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WELCOME BACK!

WELCOME BACK!. UNIT 1. Measurements Science & Physics. Hi…My Name is. Dr. P. 3.1. Using and Expressing Measurements. measurement : a quantity with both a number and a unit . Measurements are super important for experimental sciences.

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  1. WELCOME BACK! UNIT 1 Measurements Science & Physics Hi…My Name is Dr. P

  2. 3.1 Using and Expressing Measurements • measurement: a quantity with both a number and a unit. • Measurements are super important for experimental sciences. • We must be able to make measurementsaccurately and precisely.

  3. 3.1 Using and Expressing Measurements • a really big number like 100,000,000,000,000 • (atoms in a cell) • or really small number like 0.00000000001 meter • (size of an atom) • can be written withoutzeroes • by using powers of 10. • Scientific • Notation

  4. 3.1 Using and Expressing Measurements • 100,000,000,000,000 = 1 x 1014 atoms • (atoms in a cell) • 0.00000000001 meter = 1 x 10-11 meters • (size of an atom) • Scientific • Notation

  5. 3.1 Accuracy, Precision, and Error • Accuracy: • how closea measurement is • to the actualor truevalue. • Precision: • how closethe measurements are • to each another. Accuracy, Precision, and Error

  6. ACCURACY vs. PRECISION

  7. 3.1 Accuracy, Precision, and Error

  8. Quick Quiz! • 1. Which of the following expressions has NOT been correctly changed to sci. not.? • 0.00456 = 4.56  10–3 • 0.0000254 = 2.54  10–5 • 8,426,000 = 8.426  106 • 45,200 = 4.52  103

  9. Quick Quiz • 2. Which set of measurements of a 2.00-g object is the most precise? • 2.00 g, 2.03 g, 1.98 g • 2.10 g, 2.00 g, 2.20 g • 2.05 g, 2.04 g, 2.05 g • 1.50 g, 2.00 g, 2.50 g

  10. 3.1 Significant Figures in Measurements

  11. 3.2-3.3 The International System of Units • These signs show distances as numbers with no units. • Without the units, it is impossible to communicate the measurement to others. When you make a measurement, you must assign the correct units to the numerical value.

  12. 3.2-3.3 Units and Quantities • Measuring with SI Units • Length(m) meter • Volume(L) Liter • Mass(g) gram • Temp(K) Kelvin or (0C) Celsius

  13. 3.2-3.3 Units and Quantities • The volume of 20 drops of liquid from a medicine dropper is approximately 1 mL.

  14. 3.2-3.3 Units and Quantities • A sugar cube has a volume of 1 cm3. • 1 mL = 1 cm3

  15. 3.2-3.3 Units and Quantities • A gallon of milk has about twice the volume of a 2-L bottle of soda. 1 gal = 3.8 L

  16. 3.2-3.3 Units and Quantities • A 250 lb. person would weigh 113 kg 1 kg = 2.2 lb

  17. 3.2-3.3 Units and Quantities • Units of Temperature • Temperature is a measure of • average kinetic energy (heat) of particles.

  18. 373 K 273 K no KE

  19. 3.2-3.3 Units and Quantities • Converting from K to 0C and back is easy. • You simply add or subtract273 K = oC + 273

  20. Use the equation K = oC + 273 = 37 + 273 = 310 K

  21. Quick Quiz • 1. Which of the following is the SI unit for mass? • meter • gram • liter • mole

  22. Quick Quiz • 2. A temperature of 30 0C is equal to • 303 K. • 300 K. • 243 K. • 247 K.

  23. Converting Between Units Converting between units is EASY! Just use the… The Decimal Mover Trick 3.2-3.3 Metric Conversions

  24. 1.3 Metric Conversions 3.2-3.3 The Decimal Mover Trick k - - d c m m L g

  25. 3.2-3.3 • Convert each of the following. • 15 cm = ___ m • 7.38 kg = ___ g • 607 mL = ___ L • 94.5 g = ___ kg

  26. 1. How many mL in 2 L? a. 200 mL b. 0.200 mL c. 0.002 mL d. 2000 mL Quick Quiz!

  27. 2. How many mg are in 1.34 g? 1.34  10–3 13.4 134 1340 Quick Quiz

  28. m v d • Density: the ratio of an object’s • masstovolume. m v d =

  29. Density dependsonly the substance, not the size of the sample. 1 piece Aluminum d = 2.70 g/cm3 2 pieces Aluminum d = ??? g/cm3

  30. m v d Calculating Density A copper penny has a mass of 3.1 g, and a volume of 0.35 cm3. What is the density copper? m v d = 3.1 g 0.35 cm3 d = d = 8.9 g/cm3

  31. m v d Calculating Density A cup of slime has a volume of 100 mL, and a mass of 158 g. What is the density of the slime? m v d = 158 g 100 mL d = d = 1.58 g/mL

  32. m v d Quick Quiz! • 1. If 50.0 mL of yellow llama snot have a mass of 275 g, then the density of yellow llama snot is • 0.182 g/mL. • 0.727 g/mL. • 1.37 g/mL. • 5.50 g/mL.

  33. m v d Quick Quiz! • 2. Green llama snot has a density of 10 g/mL. What is the mass (in grams) of 1 Liter of green llama snot? • 10 g • 0.10 g • 1 x 10-2 g • 1 x 104 g

  34. What is Science? Scientia (Latin) – meaning knowledge Science is a way of knowingbased on testable claims supported by… ObservationandExperimentation leading to Empirical Knowledge

  35. What is NOT Science? Non-science and Pseudoscience feeling, authority emotion, religion astrology, phrenology numerology Non-science:cannot be verified empirically. (obs. & exp.) Pseudoscience:claims to be science, but cannot be verified empirically. (obs. & exp.)

  36. Science & Physics Science is the study of nature’s rules. Physics is the most basic science.

  37. You can understand other sciences much better if you first understand physics. • Biology is about complex matter that is alive. • Chemistry is about matter and how it changes. • PHYSICS is the most basic of all the sciences. Physics is about basics like motion, forces, energy, matter, heat, sound, light, and the composition of atoms.

  38. Why Study • Physics? • What are three general reasons to study Physics?

  39. Explain the Natural World • (understand how things work) Water Table Salt

  40. Prepare For a Career

  41. Be an Informed Citizen • Knowledge of chemistry and other sciences can help you evaluate the data presented, arrive at an informed opinion, and take appropriate action.

  42. The Process of Science • How do you DO science? • (are there any steps?)

  43. The process of science is a logical, organized approach to solving a scientific problem. • Steps include: • Ask Question • Observe • Hypothesis • Experiment • Theory • Communicate Results (explain) (test) (conclusion)

  44. SCIENTIFIC METHOD

  45. Make Observations • Observation: • using your senses to obtain information • Suppose you try to turn on a flashlight and it doesn’t light. An observation can lead to a question: What’s wrong with the flashlight?

  46. Form a Hypothesis • Hypothesis: a proposed explanation for an observation. • You guess that the flashlight needs new batteries based on previous observations. You can test your hypothesis by putting new batteries in the flashlight. If the flashlight lights, you can be fairly certain that your hypothesis is correct.

  47. Design an Experiment • Experiment: testof a hypothesis • Variables (can change) • - independent: you change it. • - dependent: you observe it. (it depends on what you changed) • - control: you leave it unchanged. • (to compare it with the results)

  48. Develop a Theory • Once a hypothesis is supported by repeated experimentation, it may become a theory. • Theory: a well-tested explanation for a set of observations • A theory may need to be revised to explain new observations or results

  49. Communicate Results It’s important to share a new theory through collaboration and communication. (sharing) peer-reviewed journal or conference work with others Why? review & question datafind errors in: data, conclusion, experiment revise theory

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