Introduction, Scientific Method, Measurements

1. Introduction, Scientific Method, Measurements • Learning Objectives • Physical Sciences • Scientific Method • Standard Units • Fundamental and Derived Quantities • Converting Units

2. Physical Sciences (Latin scientia meaning knowledge) An organized body of knowledge about the natural Universe, and the processes by which that knowledge Is acquired and tested SCIENCES SOCIAL SCIENCES NATURAL SCIENCES PHYSICAL SCIENCES BIOLOGICAL SCIENCES PHYSICS CHEMISTRY ASTRONOMY METEOROLOGY GEOLOGY Concerned with the basics principles of matter & energy Deals with the composition, structure, and reactions of matter. Study of the universe, which is the totality of all matter, energy, space, and time. Study of the atmosphere, from the ground in outer space. Science of the planet Earth-its composition, structure, processes, and history.

3. Scientific Method How can we come to understand the Universe? Epistemology: study (or philosophy) of knowledge. Ways of knowing: Fideism: acceptance of an idea, theory, or explanation only on the evidence of a “higher authority”. Religious beliefs, based on faith or revelation. Science: a systematic method of observation and experimentation. Based on “evidence” and experimental observation The Universe – all which is observable The part we (think) we understand The part we see but do not understand

4. Scientific Method Scientific revolution of the 1600s was due primarily to an adoption of the scientific method by Galileo, Newton, and Boyle. Hypothesis: a very tentative, possible answer or an educated guess Measurement: a quantitative observation Experiment: an observation of natural phenomena carried out in a controlled manner Ockham’s Razor: In choosing between two seemingly valid explanations of a particular phenomenon, the simpler and more general one is preferred. Theory: a well-tested explanation of a broad segment of natural phenomena

5. Scientific Method • Limitations: • Deals only with the natural world and never invokes supernatural explanations • Does not attempt to answer questions as the purpose of the universe or life. • These questions are for philosophy and religion

6. Scientific Method Beware of Pseudoscience! Pseudoscience – the dogmatic and irrational belief in an appealing idea that appears scientific but that is not supported by scientific methods. * Astrology (from ancient Babylonian culture) * UFO-ology (popular culture and mistrust of government) * “structure –altered water” (commercial quackery) How can you recognize a pseudoscience?

7. Mathematical Nature of Science • Newton and Leibniz  Calculus • Mathematics is the only language precise enough to accurately describe the laws of nature.  isomorphism • Skills needed for success in this course • Algebra • Basic Trigonometry • Graphical Analysis Do not worry about your difficulties in Mathematics. I can assure you mine are still greater. – Albert Einstein

8. Measurements - Units We need numbers in order to accurately take measurements • When executing the scientific method we must perform experiments  measurements  data • Express measurements using units (i.e. metric units, English units, etc.) • Unfortunately American students must learn both systems! • Units allow us to describe things numerically • Measurement standards – a fixed and reproducible value for the purpose of taking accurate measurements How do we know the length of a meter, yard? • Human arm, standard for length, cubit – Egyptians • King Loius XIV, length of the royal foot • Distance from equator to north pole • Modern standard, distance light,travels in 1/299,792,458 s

9. The sizes of things: What does 1025 mean? What does 102 mean? 102 = 10  10 = 100 notice that the 2 tells us how many zeros there are in the answer! 10  10  10  10  10  10  10  10  10  10  10  10  10  10  10  10  10  10  10  10  10  10  10  10  10 = 10,000,000,000,000,000,000,000,000 What does 10 -25 mean? What does 10 -2 mean? 10 -2 = 0.1  0.1 = 0.01 notice that the -2 tells us how many places to the left we move the decimal point! 0.1  0.1  0.1  0.1  0.1  0.1  0.1  0.1  0.1  0.1  0.1  0.1  0.1  0.1  0.1  0.1  0.1 0.1  0.1  0.1  0.1  0.1  0.1  0.1  0.1 = 0.0000000000000000000000001 This type of notation is called “scientific notation” it is used to represent very large and very small numbers in a manner that is efficient and easy to do.

10. Units • Mass: the kilogram • One kilogram is the mass of a particular platinum-iridium cylinder kept at the International Bureau of Weights and Standards, Sèvres, France. one kilogram weighs slightly less than one kilogram

11. Units • Time: the second • One second is the time for radiation from a cesium-133 atom to complete 9,192,631,770 oscillation cycles.

12. Units • Fundamental units – fundamental because they are the most basic quantities or properties • Length (International System, SI meter (m), British  foot (ft)) • Mass (SI gram (gr), British  slug (sl)) • Time (SI & British  second (s)) • Derived units – combinations of fundamental units • Speed (SI  m/s, British  ft/s) • Acceleration (SI  m/s2, British  ft/s2) • Force = mass × acceleration (SI  kg·m/s2 = Newton (N), British  pounds (lbs)

13. Units MKS : Meter-Kilogram-Second CGS: Centimeter-Gram-Second Sometimes even the derived units are called different names because they are so cumbersome. Typically these units are named after a scientist that contributed to it’s origin. Force = mass  Acceleration = (kg  m)/s2 = NEWTON

14. these cancel ! Converting Units of Measurement – Dimensional Analysis • It is often the case that we must convert from one set of units to another. • Suppose we want to convert 316 ft to its equivalent in meters Example: How many kilometers is 50,000 inches? left with the units we want ! The order that you apply the conversions makes no difference in the end!

15. Converting Units of Measurement – Dimensional Analysis If I drive 10 m/s in a school zone posted 20 miles/hour, am I speeding? Here we must convert two things: meters to miles, and seconds to hours Conversions are a breeze with the metric system because it is based on powers of 10!

16. Converting Units of Measurement – Dimensional Analysis What if I had 10 milliliters and needed to convert this to kiloliters?

17. Converting Units of Measurement – Dimensional Analysis Kind Hector Decked Mr. Deci at the Cinema on Monday. K H D M D C M Each word represents one of the powers of ten in the metric system!!

18. Converting Units of Measurement – Dimensional Analysis K H D M D C M So let’s look at how this works using the example we just did. What if I had 10 milliliters and needed to convert this to kiloliters? K H D M D C M 10.0 mL = ?? kL K H D M D C M Notice that I had to move over 6 letters to get to the “K” (or Kilo). So this corresponds to the number (and direction) of spaces I have to move my decimal! 10.0 mL = 0.00001 kL Let’s try another example! Go to H-ITT Question

19. Converting Units of Measurement – Dimensional Analysis We can use converting units to solve some neat problems. How about this. If I know that a stack of 1,000 - $1 bills is = 1 inch in height Could I jump over $1,000,000? Where would we start? ???

20. Dimensional Analysis • Any valid physical formula must be dimensionally consistent – each term must have the same dimensions From the table: Distance = velocity × time Velocity = acceleration × time Energy = mass × (velocity)2