1. Units and Measurement Physics Mr. Austin International Space Station http://apod.nasa.gov/apod/image/0706/iss_sts117_big.jpg

2. What is Physics? The study of the relation between energy and matter The study of: –Motion –Heat –Light –Energy –Much More!

3. Math and Units Math- the language of Physics SI Units – International System – MKS Meter m Mass kg Time s National Bureau of Standards Prefixes

4. SI Unit Prefixes - Part I NameSymbolFactor tera-T10 12 giga-G10 9 mega-M10 6 kilo-k10 3 hecto-h10 2 deka-da10 1

5. SI Unit Prefixes- Part II NameSymbolFactor deci-d10 -1 centi-c10 -2 milli-m10 -3 micro-μ10 -6 nano-n10 -9 pico-p10 -12 femto-f10 -15

6. SI Unit Prefixes for Length NameSymbol gigameterGm10 9 megameterMm10 6 kilometerkm10 3 decimeterdm10 -1 centimetercm10 -2 millimetermm10 -3 micrometerμmμm10 -6 nanometernm10 -9 picometerpm10 -12

7. The Seven Base SI Units QuantityUnitSymbol Lengthmeterm Masskilogramkg TemperaturekelvinK Timeseconds Amount of Substance molemol Luminous Intensitycandelacd Electric Currentamperea

8. Derived SI Units (examples) QuantityunitSymbol Volumecubic meterm3m3 Densitykilograms per cubic meter kg/m 3 Speedmeter per secondm/s Newtonkg m/ s 2 N EnergyJoule (kg m 2 /s 2 )J PressurePascal (kg/(ms 2 )Pa

9. Scientific Notation M x 10 n M is the coefficient 1<M<10 10 is the base n is the exponent or power of 10

10. Other Examples: 5450000 = 5.45E+6 or 5.45 x 10^6

11. Numbers less than 1 will have a negative exponent. A millionth of a second is: 0.000001 s or 1x10 -6 s or 1.0E-6 s

12. Write in Scientific Notation 3250 = –3.250 x 10 3.000435 = –4.35 x 10 -4 425620000 = –4.2562 x 10 8

13. Factor-Label Method of Unit Conversion Example: Convert 5km to m: Multiply the original measurement by a conversion factor. NEW UNIT 85km x 1,000m = 85,000m 1km OLD UNIT

14. Factor-Label Method of Unit Conversion: Example Example: Convert 789m to km: 789m x 1km =0.789km= 7.89x10 -1 km 1000m

15. Convert 75.00 km/h to m/s 75.00 km x 1000 m x 1 h___ = 20.83m/s h 1 km 3600 s

16. Accuracy - a measure of how close a measurement is to the true value of the quantity being measured.

17. Example: Accuracy Who is more accurate when measuring a book that has a true length of 17.0cm? Susan: 17.0cm, 16.0cm, 18.0cm, 15.0cm Amy: 15.5cm, 15.0cm, 15.2cm, 15.3cm

18. Precision – a measure of how close a series of measurements are to one another. A measure of how exact a measurement is.

19. Example: Precision Who is more precise when measuring the same 17.0cm book? Susan: 17.0cm, 16.0cm, 18.0cm, 15.0cm Amy: 15.5cm, 15.0cm, 15.2cm, 15.3cm

20. Example: Evaluate whether the following are precise, accurate or both. Accurate Not Precise Not Accurate Precise Accurate Precise

21. Solving Word Problems Analyze –List knowns and unknowns. –Draw a diagram. –Devise a plan. –Write the math equation to be used. Calculate –If needed, rearrange the equation to solve for the unknown. –Substitute the knowns with units in the equation and express the answer with units. Evaluate –Is the answer reasonable?

22. Practice! Please complete the following problems in class. What you do not finish will be homework to be turned in tomorrow. Pg. 24 #34, 36, 37, 41, 50, 51, 56, 67, 84, 85. Read pages 9 and 10 and answer # 49 from pg. 25 Short Quiz Tomorrow after HW review