2. Phys 110 Dr Mymona Abutalib Tel:0505622285 mabutalib@kau.edu.sa Office hours: S-M-W 9-11 am Coordinator Dr najlaa alharbi najlaa24@hotmail.com Read the book Think! Ask questions Attendthe tutorials Informationis key No pain no gain ☺

3. Objectives After this lecture you should be able to… Differentiate Explain Define Convert Apply Between base and derived quantities Standards of measurements The International system of units Units using the chain-link method The scientific notation to numbers

4. Base quantities Physical Quantities Physics is based on measurement of Physical Quantities. For example: length, time, mass, temperature, pressure. Physical Quantities A ssumedto be independent of each other. Defined in terms of base quantitiesvia equations. Length, mass and time. Length Time Velocity  Derived quantities

6. Derived SI Units (examples) QuantityunitSymbol Volumecubic meter m3m3m3m3 Densitykilograms per cubic meter kg/m 3 Speedmeter per secondm/s Newtonkg m/ s 2N EnergyJoule (kg m 2 /s 2 )J PressurePascal (kg/(ms 2 )Pa

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

8. 653000 000 m = 0.000 00729 s = 6.53 E 8 m 7.29 E -6 s To express a very large and very small quantity we use :

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

10. Numbers less than 1 will have a negative exponent. A millionth of a second is: 0.000001 sec 1x10 -6 1.0E-6 1.0^-6

11. 2.67x10 9 watt = 3.21x10 -6 s =

12. We often need to change the units in the physical quantity by a method called chain link conversion In this method we multiply the original measurement by a conversion factor. is a ratio of units that is equal to unity. is a ratio of units that is equal to unity.

13. 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. 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. بعض المصطلحات الموجودة في Ch1 المصطلح العلمي ( انجليزى ) المصطلح العلمي ( العربي ) Measurments and Dimension الكميات والقياسات Physical quantities الكميات الفيزيائية Base quantities الكميات الاساسية Derived quantities الكميات المشتقة Unit وحدة Length الطول Time الزمن Mass الكتلة Density الكثافة Scientific notation رموز علمية Exponent of ten اس عشرة Power of ten قوة العشرة Changing Units تحويل اوتغير وحدات conversion Factor عامل التحويل Factor عامل Prefixes of units الوحدات البدائية