1 / 21

PHYSICS UNIT 0: FOUNDATIONS

PHYSICS UNIT 0: FOUNDATIONS. MEASUREMENT. Units of Measure - Metric System (SI) Fundamental Units : defined by scientists Dimension Unit Symbol length meter m mass kilogram kg time second s current ampere A temperature Kelvin K

stone-caldwell
Download Presentation

PHYSICS UNIT 0: FOUNDATIONS

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. PHYSICS UNIT 0: FOUNDATIONS

  2. MEASUREMENT • Units of Measure - Metric System (SI) • Fundamental Units: defined by scientists Dimension Unit Symbol length meter m mass kilogram kg time second s current ampere A temperature Kelvin K • Derived Units: combinations of fundamental units • ex: area measured in m2, density measured in g/cm3

  3. Measurement • Important Ranges of Magnitudes to remember • Distances – size of a nucleus(10^-15 m) to size of the universe (10^25 m) • Masses – mass of an electron(10^-30 kg) to mass of the universe (10^53 kg) • Times – time for light to pass a nucleus (10^-23 s) to age of the universe (10^18 s) • So what are the order of magnitude differences?

  4. MEASUREMENT • prefixes: for larger or smaller quantities Prefix Symbol Value Example Giga G 109 30 Gb = 30,000,000,000 b mega M 106 2.1 Mm = 2,100,000 m kilo k 103 3.5 kg = 3500 g deci d 10–1 8.7 dL = 0.87 L centi c 10–2 5.9 cs = 0.059 s milli m 10–3 7.2 mmol = 0.0072 mol microm10–6 4.4 mm = 0.0000044 m nano n 10–9 9.0 ng = 0.000000009 g

  5. MEASUREMENT • conversions from one prefix to another: mega kilo none deci centi milli micro nano 1000 1000 10 10 10 1000 1000 larger units smaller units dividemultiply

  6. MEASUREMENT • conversion factors - multipliers that change units without changing equation’s overall value (factors have a value of 1) • ex: 1 in = 2.54 cm factors: • set up so units cancel • ex:find the kilometers in 1 mile

  7. MATHEMATICS • Scientific Notation: shorthand for large & small numbers • form: 0.00 × 10 0(number ≥ 1 & < 10 × power of 10) • ex: 450,000,000 = 4.5 × 100,000,000 = 4.5 × 108 • 0.0000036 = 3.6 × 0.000001 = 3.6 × 10–6

  8. EE 5 8 . 4 EE . 6 3 6 +/- MATHEMATICS • Scientific Calculators • 4.5 × 108 is entered and may appear as or • 3.6 × 10–6 is entered and may appear as or • some calculators use instead of 4.5 08 4.5 08 3.6 -06 3.6 -06 EE EXP

  9. UNCERTAINTY • Significant Figures • shorthand way of showing precision & uncertainty • number of sig. fig's = # of digits BUT don't count beginning zeroes AND don't count ending zeroes unless there is a decimal. 234.15 14.080 560,000 0.00282 5.6 × 105

  10. UNCERTAINTY • Significant Figures • calculations cannot be more exact than measurements: • a. round off to least number of sig. fig's ex:(1.05)(39.04)(251,000)(0.0044)=45271.565 round off to 2 sig. fig's = 45,000 • b. round off once, at the end of all calculations • c. when in doubt, round to 3 sig. fig's

  11. PHYSICS UNIT 0: FOUNDATIONS

  12. The 2 Major Types of Error in Experimental Physics • Systematic Error- Errors inherent in the system of data taking. (Can not be cancelled with lots of data) • Example – using an uncalibrated scale. • Random Error- are inherently unpredictable. (Can be cancelled out with lots of data) • Example – stopping a stop watch too early sometimes and too late other times.

  13. Systematic Error • There are 3 major types of systematic error • human error: mistakes in reading & recording • make repeat measurements (Do not include in lab write up, instead fix human problem). • method error: mistakes in measurement methods • choose the best method & use it consistently. • instrument error: mistakes due to damaged instruments • check instrument calibration, use carefully.

  14. UNCERTAINTY • Accuracy- the degree of closeness of experimental result with theoretical result. (Low systematic error) • Assessing accuracy: percent error(if you know what the measurement should have been by other methods)

  15. UNCERTAINTY • Precision: limitations of a measuring instrument (Sensitivity) • the more digits you can read, the more precision (less uncertainty) • A precise measuring device will take repeated measurements that are close to each other.

  16. GRAPHING • purpose: finding patterns & relationships • drawing graphs: • title graph • dependent variable: y, independent variable:x • Uncertainty in data should be included on graph • Include the equation that best fits the data • choose & show scale on each axis - fit all data • label each axis: measured quantity & units

  17. graph interpretation: linear relationship: as x increases, y increases (y  x) y = mx+b m: slope, b:y-intercept Said “The distance traveled by a car moving at constant speed is directly proportional to the time travelled.”. GRAPHING

  18. graph interpretation: quadratic relationship: as x increases, y increases (y  x2) y = kx2 k: appropriate constant Said “The bacteria population grew exponentially with time.” GRAPHING

  19. graph interpretation: inverse relationship: as x increases, y decreases (y  1/x) y = k/x k: appropriate constant Said “For any given constant force acting on an object there is an inverse relationship between and object’s mass and it’s acceleration” GRAPHING

  20. UNIT 0 QUIZ PREVIEW • Concepts Covered: • metric system: units, prefixes & conversions • accuracy, precision & significant figures • math skills – algebra, scientific notation, estimation, types of graphs. • What’s On The Quiz: • __ multiple choice/matching • __ problems

  21. Equations for Propagating Error Sum Difference Product Quotient

More Related